A hat is a head covering which is worn for various reasons, including protection against weather conditions, ceremonial reasons such as university graduation, religious reasons, safety, or as a fashion accessory. In the past, hats were an indicator of social status. In the military, hats may denote nationality, branch of service, rank or regiment. Police typically wear distinctive hats such as peaked caps or brimmed hats, such as those worn by the Royal Canadian Mounted Police. Some hats have a protective function. As examples, the hard hat protects construction workers' heads from injury by falling objects and a British police Custodian helmet protects the officer's head, a sun hat shades the face and shoulders from the sun, a cowboy hat protects against sun and rain and a Ushanka fur hat with fold-down earflaps keeps the head and ears warm. Some hats are worn for ceremonial purposes, such as the mortarboard, which is worn (or carried) during university graduation ceremonies. Some hats are worn by members of a certain profession, such as the Toque worn by chefs. Some hats have religious functions, such as the mitres worn by Bishops and the turban worn by Sikhs.
While there are not many official records of hats before 3000 BC, they probably were commonplace before that. The 27-30,000 year old Venus of Willendorf figurine may depict a woman wearing a woven hat. One of the earliest known confirmed hats was worn by a bronze age man (nicknamed Ötzi) whose body (including his hat) was found frozen in a mountain between Austria and Italy, where he'd been since around 3250 BC. He was found wearing bearskin cap with a chin strap, made of several hides stitched together, essentially resembling a Russian fur hat without the flaps.
One of the first pictorial depictions of a hat appears in a tomb painting from Thebes, Egypt, which shows a man wearing a conical straw hat, dated to around 3200 BC. Hats were commonly worn in ancient Egypt. Many upper-class Egyptians shaved their heads, then covered it in a headdress intended to help them keep cool. Ancient Mesopotamians often wore conical hats or ones shaped somewhat like an inverted vase.
Other early hats include the Pileus, a simple skull-like cap; the Phrygian cap, worn by freed slaves in Greece and Rome (which became iconic in America during the Revolutionary War and the French Revolution, as a symbol of the struggle for liberty against the Monarchy); and the Greek petasos, the first known hat with a brim. Women wore veils, kerchiefs, hoods, caps and wimples.
Like Ötzi, the Tollund Man was preserved to the present day with a hat on, probably having died around 400 BC in a Danish bog, which mummified him. He wore a pointed cap made of sheepskin and wool, fastened under the chin by a hide thong.
In the Middle Ages, hats were a marker of social status and used to single out certain groups. The 1215 Fourth Council of the Lateran required that all Jews identify themselves by wearing the Judenhat ("Jewish hat"), marking them as targets for anti-Semitism. The hats were usually yellow and were either pointed or square.
In the Middle Ages, hats for women ranged from simple scarves to elaborate hennin, and denoted social status. Structured hats for women similar to those of male courtiers began to be worn in the late 16th century. The term 'milliner' comes from the Italian city of Milan, where the best quality hats were made in the 18th century. Millinery was traditionally a woman's occupation, with the milliner not only creating hats and bonnets but also choosing lace, trimmings and accessories to complete an outfit.
In the first half of the 19th century, women wore bonnets that gradually became larger, decorated with ribbons, flowers, feathers, and gauze trims. By the end of the century, many other styles were introduced, among them hats with wide brims and flat crowns, the flower pot and the toque. By the middle of the 1920s, when women began to cut their hair short, they chose hats that hugged the head like a helmet.
The tradition of wearing hats to horse racing events began at the Royal Ascot in Britain, which maintains a strict dress code. All guests in the Royal Enclosure must wear hats. This tradition was adopted at other horse racing events, such as the Kentucky Derby in the United States.
Extravagant hats were popular in the 1980s, and in the early 21st century, flamboyant hats made a comeback, with a new wave of competitive young milliners designing creations that include turban caps, trompe-l'oeil-effect felt hats and tall headpieces made of human hair. Some new hat collections have been described as "wearable sculpture." Many pop stars, among them Lady Gaga, have commissioned hats as publicity stunts.
One of the most famous London hatters is James Lock & Co. of St James's Street. The shop claims to be the oldest operating hat shop in the world. Another was Sharp & Davis of 6 Fish Street Hill. In the late 20th century, museums credited London-based David Shilling with reinventing hats worldwide. Notable Belgian hat designers are Elvis Pompilio and Fabienne Delvigne (Royal warrant of appointment holder), whose hats are worn by European royals. Philip Treacy OBE is an award-winning Irish milliner whose hats have been commissioned by top designers and worn at royal weddings. In North America, the well-known cowboy-hat manufacturer Stetson made the headgear for the Royal Canadian Mounted Police and the Texas Rangers. John Cavanagh was one of the notable American hatters. Italian hat maker Borsalino has covered the heads of Hollywood stars and the world's rich and famous.
The Philippi Collection is a collection of religious headgear assembled by a German entrepreneur, Dieter Philippi, located in Kirkel. The collection features over 500 hats, and is currently the world's largest collection of clerical, ecclesiastical and religious head coverings.
This is a short list of some common and iconic examples of hats. There is a longer version at List of hat styles.
|Ascot cap||A hard men's cap, similar to the flat cap, but distinguished by its hardness and rounded shape.|
|Balmoral bonnet||Traditional Scottish bonnet or cap worn with Scottish Highland dress.|
|Baseball cap||A type of soft, light cotton cap with a rounded crown and a stiff, frontward-projecting bill.|
|Beanie||A brimless cap, with or without a small visor, once popular among school boys. Sometimes includes a propeller.|
Note: In New Zealand, Australia, the United States and the United Kingdom, "beanie" also or otherwise refers to the tuque.
|Bearskin||The tall, furry hat of the Brigade of Guards' full-dress uniform, originally designed to protect them against sword-cuts, etc. Commonly seen at Buckingham Palace in London, England. Sometimes mistakenly identified as a busby.|
|Beret||A soft round cap, usually of woollen felt, with a bulging flat crown and tight-fitting brimless headband. Worn by both men and women and traditionally associated with Basque people, France, and the military. Often part of [European?] schoolgirls' uniform during the 1920s, '30s and '40s.|
|Bicorne||A broad-brimmed felt hat with brim folded up and pinned front and back to create a long-horned shape. Also known as a cocked hat. Worn by European military officers in the 1790s and, as illustrated, commonly associated with Napoleon.|
|Bowler / Derby||A hard felt hat with a rounded crown created in 1850 by Lock's of St James's, the hatters to Thomas Coke, 2nd Earl of Leicester, for his servants. More commonly known as a Derby in the United States.|
|Chullo||Peruvian or Bolivian hat with ear-flaps made from vicuña, alpaca, llama or sheep's wool.|
|Cloche hat||A bell-shaped ladies' hat that was popular during the Roaring Twenties.|
|Cricket cap||A type of soft cap traditionally worn by cricket players.|
|Sombrero Cordobés||A traditional flat-brimmed and flat-topped hat originating from Córdoba, Spain, associated with flamenco dancing and music and popularized by characters such as Zorro.|
|Conical Asian hat||A conical straw hat associated with East and Southeast Asia. Sometimes known as a "coolie hat", although the term "coolie" may be interpreted as derogatory.|
|Coonskin cap||A hat, fashioned from the skin and fur of a raccoon, that became associated with Canadian and American frontiersmen of the 18th and 19th centuries.|
|Custodian helmet||A helmet traditionally worn by British police constables while on foot patrol.|
|Deerstalker||A warm, close-fitting tweed cap, with brims front and behind and ear-flaps that can be tied together either over the crown or under the chin. Originally designed for use while hunting in the climate of Scotland. Worn by –and so closely associated with – the character Sherlock Holmes.|
|Fedora||A soft felt hat with a medium brim and lengthwise crease in the crown.|
|Fez||Red felt hat in the shape of a truncated cone, common to Arab-speaking countries.|
|Fulani hat||A conical plant fiber hat covered in leather both at the brim and top, worn by men of the Fulani people in West Africa.|
|Keffiyah||Three piece ensemble consisting of a Thagiyah skull cap, Gutrah scarf, and Ogal black band. Gutrahs are plain white or checkered, denoting ethnic or national identities..|
|Hard hat||A rounded rigid helmet with a small brim predominantly used in workplace environments, such as construction sites, to protect the head from injury by falling objects, debris and bad weather.|
|Kippah||A hemispherical cap worn by Jews to fulfill the customary requirement held by halachic authorities that the head be covered at all times.|
|Kufi||A brimless, short, rounded cap worn by Africans and people throughout the African diaspora.|
|Mitre||Distinctive hat worn by bishops in the Roman Catholic Church, Eastern Orthodox Church, and the Anglican Communion.|
|Montera||A crocheted hat worn by bullfighters.|
|Panama||Straw hat made in Ecuador.|
|Phrygian Cap||A soft conical cap pulled forward. In sculpture, paintings and caricatures it represents freedom and the pursuit of liberty. The popular cartoon characters The Smurfs wear white Phrygian caps.|
|Pillbox hat||A small hat with straight, upright sides, a flat crown, and no brim.|
|Pith Helmet||A lightweight rigid cloth-covered helmet made of cork or pith, with brims front and back. Worn by Europeans in tropical colonies in the 1800s.|
|Rastacap||A tall, round, usually crocheted and brightly colored, cap worn by Rastafarians and others with dreadlocks to tuck their locks away.|
|Santa Hat||A floppy pointed red hat trimmed in white fur traditionally associated with Christmas.|
|Sombrero||A Mexican hat with a conical crown and a very wide, saucer-shaped brim, highly embroidered made of plush felt.|
|Tam o'Shanter||A traditional flat, round Scottish cap usually worn by men (in the British military sometimes abbreviated ToS).|
|Top hat||Also known as a beaver hat, a magician's hat, or, in the case of the tallest examples, a stovepipe hat. A tall, flat-crowned, cylindrical hat worn by men in the 19th and early 20th centuries, now worn only with morning dress or evening dress. Cartoon characters Uncle Sam and Mr. Monopoly are often depicted wearing such hats. Once made from felted beaver fur.|
|Toque||(informally, "chef's hat") A tall, pleated, brimless, cylindrical hat traditionally worn by chefs.|
|Tricorne||A soft hat with a low crown and broad brim, pinned up on either side of the head and at the back, producing a triangular shape. Worn by Europeans in the 18th century. Larger, taller, and heavily ornamented brims were present in France and the Papal States.|
|Tuque||In Canada, a knitted hat, worn in winter, usually made from wool or acrylic. Also known as a ski cap, knit hat, knit cap, sock cap, stocking cap, toboggan, watch cap, or goobalini. In New Zealand, Australia, the United States and the United Kingdom, the term "beanie" is applied to this cap.|
|Turban||A headdress consisting of a scarf-like single piece of cloth wound around either the head itself or an inner hat.|
|Ushanka||A Russian fur hat with fold-down ear-flaps.|
|Zucchetto||Skullcap worn by clerics typically in Roman Catholicism.|
Hat sizes are determined by measuring the circumference of a person's head about 1 centimetre (1⁄2 in) above the ears. Inches or centimeters may be used depending on the manufacturer. Felt hats can be stretched for a custom fit. Some hats, like hard hats and baseball caps, are adjustable. Cheaper hats come in "standard sizes", such as small, medium, large, extra large: the mapping of measured size to the various "standard sizes" varies from maker to maker and style to style, as can be seen by studying various catalogues, such as Hammacher Schlemmer.
|size||Youth S/M||Youth L/XL||XXS||XS||S||M||L||XL||XXL||XXXL|
|Circumference in cm||34||43||47||48||49||50||51–52||53–54||55–56||57–58||59–60||61–62||63–64||65–66|
|Circumference in inches||13⅜||17||18½||18¾||19¼||19¾||20–20½||20–21¼||21–22||22–22½⅞||23–23½⅝||24–24⅜||24¾–25¼||25–26|
|UK hat size||5||5¾||6||6||6–6¼||6–6½||6–6¾||7–7⅛||7–7¼||7–7½||7–7¾||8–8⅛|
|US hat size||5⅞||6||6⅛||6¼||6–6½||6⅝- 6¾||6–7||7–7¼||7–7½||7–7¾||7–8||8–8¼|
|French hat size||0||½||1||1½||2–2½||3–3½||4–4½||5–5½||6–6½||7–7½||8–8½||9–9½|
A baseball cap is a type of soft cap with a rounded crown and a stiff peak projecting in front.
The front of the cap typically contains a design or a logo of sports team (namely a baseball team, or names of relevant companies, when used as a commercial marketing technique). The back of the cap may be "fitted" to the wearer's head size or it may have a plastic, Velcro, or elastic and zipper strip, adjuster so that it can be quickly adjusted to fit different wearers. The baseball cap is a part of the traditional baseball uniform worn by players, with the brim pointing forward to shield the eyes from the sun. Since the 1980s varieties of the cap have become a common fashion accessory, particularly in the United States.Bowler hat
The bowler hat, also known as a billycock, bob hat, bombín or derby (USA), is a hard felt hat with a rounded crown, originally created by the London hat-makers Thomas and William Bowler during 1849. It has traditionally been worn with semi-formal and informal attire. The bowler, a protective and durable hat style, was popular with the British, Irish, and American working classes during the second half of the 19th century, and later with the middle and upper classes in the United Kingdom, Ireland, and the east coast United States.Cowboy hat
The cowboy hat is a high-crowned, wide-brimmed hat best known as the defining piece of attire for the North American cowboy. Influenced by 19th century Mexican culture, today it is worn by many people, and is particularly associated with ranch workers in the western and southern United States, western Canada and northern Mexico, with country-western singers and ranchero singers in Mexico, and for participants in the North American rodeo circuit. It is recognized around the world as part of Old West lore. The shape of a cowboy hat's crown and brim are often modified by the wearer for fashion and to protect against weather.
It is an item of apparel that can be worn in any corner of the world, and receive immediate recognition as part of North American cowboy culture.The first western model was the open-crowned "Boss of the Plains", and after that came the front-creased Carlsbad, destined to become "the" cowboy style. The high-crowned, wide-brimmed, soft-felt western hats that followed are intimately associated with the cowboy image.Cristiano Ronaldo
Cristiano Ronaldo dos Santos Aveiro GOIH ComM (European Portuguese: [kɾiʃˈtjɐnu ʁoˈnaɫdu]; born 5 February 1985) is a Portuguese professional footballer who plays as a forward for Italian club Juventus and captains the Portugal national team. Often considered the best player in the world and regarded by many as one of the greatest players of all time, Ronaldo has a record-tying five Ballon d'Or awards, the most for a European player, and is the first player to win four European Golden Shoes. He has won 26 trophies in his career, including five league titles, five UEFA Champions League titles and one UEFA European Championship. A prolific goalscorer, Ronaldo holds the records for most official goals scored in Europe's top-five leagues (409), the UEFA Champions League (121), the UEFA European Championship (9), as well as those for most assists in the UEFA Champions League (34) and the UEFA European Championship (6). He has scored over 690 senior career goals for club and country.
Born and raised on the Portuguese island of Madeira, Ronaldo was diagnosed with a racing heart at age 15. He underwent an operation to treat his condition, and began his senior club career playing for Sporting CP, before signing with Manchester United at age 18 in 2003. After winning his first trophy, the FA Cup, during his first season in England, he helped United win three successive Premier League titles, a UEFA Champions League title, and a FIFA Club World Cup. By age 22, he had received Ballon d'Or and FIFA World Player of the Year nominations and at age 23, he won his first Ballon d'Or and FIFA World Player of the Year awards. In 2009, Ronaldo was the subject of the most expensive association football transfer when he moved from Manchester United to Real Madrid in a transfer worth €94 million (£80 million).
With Real Madrid, Ronaldo won 15 trophies, including two La Liga titles, two Copas del Rey, four UEFA Champions League titles, two UEFA Super Cups, and three FIFA Club World Cups. Real Madrid's all-time top goalscorer, Ronaldo scored a record 34 La Liga hat-tricks, including a record-tying eight hat-tricks in the 2014–15 season and is the only player to reach 30 goals in six consecutive La Liga seasons. After joining Madrid, Ronaldo finished runner-up for the Ballon d'Or three times, behind Lionel Messi, his perceived career rival, before winning back-to-back Ballons d'Or in 2013 and 2014. After winning the 2016 and 2017 Champions Leagues, Ronaldo secured back-to-back Ballons d'Or again in 2016 and 2017. A historic third consecutive Champions League followed, making Ronaldo the first player to win the trophy five times. In 2018, he signed for Juventus in a transfer worth €100 million, the highest ever paid by an Italian club and the highest fee ever paid for a player over 30 years old.
A Portuguese international, Ronaldo was named the best Portuguese player of all time by the Portuguese Football Federation in 2015. He made his senior debut for Portugal in 2003 at age 18, and has since had over 150 caps, including appearing and scoring in eight major tournaments, becoming Portugal's most capped player and his country's all-time top goalscorer. He scored his first international goal at Euro 2004 and helped Portugal reach the final. He took over full captaincy in July 2008, leading Portugal to their first-ever triumph in a major tournament by winning Euro 2016, and received the Silver Boot as the second-highest goalscorer of the tournament, before becoming the highest European international goalscorer of all-time. One of the most marketable athletes in the world, he was ranked the world's highest-paid athlete by Forbes in 2016 and 2017, as well as the world's most famous athlete by ESPN in 2016, 2017 and 2018.Fedora
A fedora is a hat with a soft brim and indented crown. It is typically creased lengthwise down the crown and "pinched" near the front on both sides. Fedoras can also be creased with teardrop crowns, diamond crowns, center dents, and others, and the positioning of pinches can vary. The typical crown height is 4.5 inches (11 cm).
The fedora hat's brim is usually wide, approximately 2.5 inches (6.4 cm) wide, but may be wider, can be left "raw edged" (left as cut), finished with a sewn overwelt or underwelt, or bound with a trim-ribbon. "Stitched edge" means that there is one, two or more rows of stitching radiating inward toward the crown. The "Cavanagh Edge" is a welted edge with invisible stitching to hold it in place and is a very expensive treatment that can no longer be performed by modern hat factories. Fedora hats are not to be confused with small brimmed hats called trilbies.The term fedora was in use as early as 1891. Its popularity soared, and eventually it eclipsed the similar-looking homburg.Fedoras can be made of wool, cashmere, rabbit or beaver felt. These felts can also be blended to each other with mink or chinchilla and rarely with vicuña, guanaco, cervelt, or mohair. They can also be made of straw, cotton, waxed or oiled cotton, hemp, linen or leather.
A special variation is the rollable, foldaway or crushable fedora (rollable and crushable are not the same) with a certain or open crown (open-crown fedoras can be bashed and shaped in many variations). Special fedoras have a ventilated crown with grommets, mesh inlets or penetrations for a better air circulation.
Fedoras can be lined or unlined and have a leather or cloth or ribbon sweatband. Small feathers are sometimes added as decoration. Fedoras can be equipped with a chinstrap, but this is rare.Fez
The fez (more correctly ṭarbūsh) is a felt headdress in the shape of a short cylindrical peakless hat, usually red, and sometimes with a tassel attached to the top. It is named after the city of its origins the Moroccan city Fez, the capital of the Kingdom of Morocco until 1927. The modern fez owes much of its popularity to the Ottoman era.The fez is often confused with the shashia (or, with French spelling chèchia) which is derived from the Arabic شاشية, shāshiyya. The two types of headgear are quite different: the fez is stiff, conical, and raised in shape, while the shashia is soft and its shape adheres to the top of the head, in the manner of a cap.Flat cap
A flat cap is a rounded cap with a small stiff brim in front. The hat is also known in Scotland as a bunnet in the Scots language, in Wales as a Dai cap, in New Zealand as a cheese-cutter, and in the United States as a driving cap. Cloths used to make the cap include wool, tweed (most common), and cotton. Less common materials may include leather, linen, or corduroy. The inside of the cap is commonly lined for comfort and warmth.Fourier transform
The Fourier transform (FT) decomposes a function of time (a signal) into the frequencies that make it up, in a way similar to how a musical chord can be expressed as the frequencies (or pitches) of its constituent notes. The Fourier transform of a function of time is itself a complex-valued function of frequency, whose absolute value represents the amount of that frequency present in the original function, and whose complex argument is the phase offset of the basic sinusoid in that frequency. The Fourier transform is called the frequency domain representation of the original signal. The term Fourier transform refers to both the frequency domain representation and the mathematical operation that associates the frequency domain representation to a function of time. The Fourier transform is not limited to functions of time, but in order to have a unified language, the domain of the original function is commonly referred to as the time domain. For many functions of practical interest, one can define an operation that reverses this: the inverse Fourier transformation, also called Fourier synthesis, of a frequency domain representation combines the contributions of all the different frequencies to recover the original function of time. In image processing the notion of a time domain is replaced by that of a spatial domain where the intensity of a signal is identified by its spatial position rather than at any point in time.
Linear operations performed in one domain (time or frequency) have corresponding operations in the other domain, which are sometimes easier to perform. The operation of differentiation in the time domain corresponds to multiplication by the frequency, so some differential equations are easier to analyze in the frequency domain. Also, convolution in the time domain corresponds to ordinary multiplication in the frequency domain. Concretely, this means that any linear time-invariant system, such as a filter applied to a signal, can be expressed relatively simply as an operation on frequencies. After performing the desired operations, transformation of the result can be made back to the time domain. Harmonic analysis is the systematic study of the relationship between the frequency and time domains, including the kinds of functions or operations that are "simpler" in one or the other, and has deep connections to many areas of modern mathematics.
Functions that are localized in the time domain have Fourier transforms that are spread out across the frequency domain and vice versa, a phenomenon known as the uncertainty principle. The critical case for this principle is the Gaussian function, of substantial importance in probability theory and statistics as well as in the study of physical phenomena exhibiting normal distribution (e.g., diffusion). The Fourier transform of a Gaussian function is another Gaussian function. Joseph Fourier introduced the transform in his study of heat transfer, where Gaussian functions appear as solutions of the heat equation.
The Fourier transform can be formally defined as an improper Riemann integral, making it an integral transform, although this definition is not suitable for many applications requiring a more sophisticated integration theory. For example, many relatively simple applications use the Dirac delta function, which can be treated formally as if it were a function, but the justification requires a mathematically more sophisticated viewpoint. The Fourier transform can also be generalized to functions of several variables on Euclidean space, sending a function of 3-dimensional space to a function of 3-dimensional momentum (or a function of space and time to a function of 4-momentum). This idea makes the spatial Fourier transform very natural in the study of waves, as well as in quantum mechanics, where it is important to be able to represent wave solutions as functions of either space or momentum and sometimes both. In general, functions to which Fourier methods are applicable are complex-valued, and possibly vector-valued. Still further generalization is possible to functions on groups, which, besides the original Fourier transform on ℝ or ℝn (viewed as groups under addition), notably includes the discrete-time Fourier transform (DTFT, group = ℤ), the discrete Fourier transform (DFT, group = ℤ mod N) and the Fourier series or circular Fourier transform (group = S1, the unit circle ≈ closed finite interval with endpoints identified). The latter is routinely employed to handle periodic functions. The fast Fourier transform (FFT) is an algorithm for computing the DFT.Hat-trick
A hat-trick or hat trick is the achievement of a positive feat three times in a game, or another achievement based on the number three.Knit cap
A knit cap, originally of wool (though now often of synthetic fibers) is designed to provide warmth in cold weather. Typically, the knit cap is of simple, tapering constructions, though many variants exist. Historically, the wool knit cap was an extremely common form of headgear for seamen, fishers, hunters and others spending their working day outdoors from the 18th century and forward, and is still commonly used for this purpose in Canada, Scandinavia and other cold regions of the world. Being found all over the world where climate demands a warm hat, the knit cap can be found under a multitude of local names.Medicine Hat
Medicine Hat is a city in southeast Alberta, Canada located along the South Saskatchewan River. It is approximately 169 km (105 mi) east of Lethbridge and 295 km (183 mi) southeast of Calgary. This city and the adjacent Town of Redcliff to the northwest are within Cypress County. Medicine Hat was the sixth-largest city in Alberta in 2016 with a population of 63,230.
Started as a railroad town, today Medicine Hat is served by the Trans-Canada Highway (Highway 1) and the eastern terminus of the Crowsnest Highway (Highway 3). Nearby communities considered part of the Medicine Hat area include the Town of Redcliff (abutting the city's northwest boundary) and the hamlets of Desert Blume, Dunmore, Irvine, Seven Persons, and Veinerville. The Cypress Hills (including Cypress Hills Interprovincial Park) is a relatively short distance (by car) to the southeast of the city.
Historically, Medicine Hat has been known for its large natural gas fields, being immortalized by Rudyard Kipling as having "all hell for a basement". Because of these reserves, the city is known as "The Gas City".Red Hat
Red Hat, Inc. is an American multinational software company providing open-source software products to the enterprise community. Founded in 1993, Red Hat has its corporate headquarters in Raleigh, North Carolina, with other offices worldwide.Red Hat has become associated to a large extent with its enterprise operating system Red Hat Enterprise Linux and with the acquisition of open-source enterprise middleware vendor JBoss. Red Hat also offers Red Hat Virtualization (RHV), an enterprise virtualization product. Red Hat provides storage, operating system platforms, middleware, applications, management products, and support, training, and consulting services.
Red Hat creates, maintains, and contributes to many free software projects. It has acquired several proprietary software product codebases through corporate mergers and acquisitions and has released such software under open-source licenses. As of March 2016, Red Hat is the second largest corporate contributor to the Linux kernel version 4.14 after Intel.On October 28, 2018, IBM announced its intent to acquire Red Hat for $34 billion.Red Hat Enterprise Linux
Red Hat Enterprise Linux is a Linux distribution developed by Red Hat and targeted toward the commercial market. Red Hat Enterprise Linux is released in server versions for x86-64, Power Architecture, ARM64, and IBM Z, and a desktop version for x86-64. All of Red Hat's official support and training, together with the Red Hat Certification Program, focuses on the Red Hat Enterprise Linux platform. Red Hat Enterprise Linux is often abbreviated to RHEL.
The first version of Red Hat Enterprise Linux to bear the name originally came onto the market as "Red Hat Linux Advanced Server". In 2003 Red Hat rebranded Red Hat Linux Advanced Server to "Red Hat Enterprise Linux AS", and added two more variants, Red Hat Enterprise Linux ES and Red Hat Enterprise Linux WS.
Red Hat uses strict trademark rules to restrict free re-distribution of their officially supported versions of Red Hat Enterprise Linux, but still freely provides its source code. Third-party derivatives can be built and redistributed by stripping away non-free components like Red Hat's trademarks. Examples include community-supported distributions like CentOS and Scientific Linux, and commercial forks like Oracle Linux.
In October 2018, Red Hat declared that KDE Plasma was no longer supported in future updates of Red Hat Enterprise Linux. The announcement came shortly after the announcement of the business acquisition of Red Hat by IBM for close to $34 billion USD.Search engine optimization
Search engine optimization (SEO) is the process of affecting the online visibility of a website or a web page in a web search engine's unpaid results—often referred to as "natural", "organic", or "earned" results. In general, the earlier (or higher ranked on the search results page), and more frequently a website appears in the search results list, the more visitors it will receive from the search engine's users; these visitors can then be converted into customers. SEO may target different kinds of search, including image search, video search, academic search, news search, and industry-specific vertical search engines. SEO differs from local search engine optimization in that the latter is focused on optimizing a business' online presence so that its web pages will be displayed by search engines when a user enters a local search for its products or services. The former instead is more focused on national or international searches.
As an Internet marketing strategy, SEO considers how search engines work, the computer programmed algorithms which dictate search engine behavior, what people search for, the actual search terms or keywords typed into search engines, and which search engines are preferred by their targeted audience. Optimizing a website may involve editing its content, adding content, doing HTML, and associated coding to both increase its relevance to specific keywords and to remove barriers to the indexing activities of search engines. Promoting a site to increase the number of backlinks, or inbound links, is another SEO tactic. By May 2015, mobile search had surpassed desktop search. In 2015, it was reported that Google is developing and promoting mobile search as a key feature within future products. In response, many brands are beginning to take a different approach to their Internet marketing strategies.Security hacker
A security hacker is someone who seeks to breach defenses and exploit weaknesses in a computer system or network. Hackers may be motivated by a multitude of reasons, such as profit, protest, information gathering, challenge, recreation, or to evaluate system weaknesses to assist in formulating defenses against potential hackers. The subculture that has evolved around hackers is often referred to as the computer underground.There is a longstanding controversy about the term's true meaning. In this controversy, the term hacker is reclaimed by computer programmers who argue that it refers simply to someone with an advanced understanding of computers and computer networks,
and that cracker is the more appropriate term for those who break into computers, whether computer criminal (black hats) or computer security expert (white hats). A 2014 article concluded that "... the black-hat meaning still prevails among the general public".Spamdexing
In digital marketing and online advertising, spamdexing (also known as search engine spam, search engine poisoning, black-hat Search engine optimization (SEO), search spam or web spam) is the deliberate manipulation of search engine indexes. It involves a number of methods, such as link building and repeating unrelated phrases, to manipulate the relevance or prominence of resources indexed, in a manner inconsistent with the purpose of the indexing system.It could be considered to be a part of search engine optimization, though there are many search engine optimization methods that improve the quality and appearance of the content of web sites and serve content useful to many users. Search engines use a variety of algorithms to determine relevancy ranking. Some of these include determining whether the search term appears in the body text or URL of a web page. Many search engines check for instances of spamdexing and will remove suspect pages from their indexes. Also, search-engine operators can quickly block the results-listing from entire websites that use spamdexing, perhaps alerted by user complaints of false matches. The rise of spamdexing in the mid-1990s made the leading search engines of the time less useful. Using unethical methods to make websites rank higher in search engine results than they otherwise would is commonly referred to in the SEO (search engine optimization) industry as "black hat SEO". These methods are more focused on breaking the search-engine-promotion rules and guidelines. In addition to this, the perpetrators run the risk of their websites being severely penalized by the Google Panda and Google Penguin search-results ranking algorithms.Common spamdexing techniques can be classified into two broad classes: content spam (or term spam) and link spam.The Cat in the Hat
The Cat in the Hat is a children's book written and illustrated by Theodor Geisel under the pen name Dr. Seuss and first published in 1957. The story centers on a tall anthropomorphic cat, who wears a red and white-striped hat and a red bow tie. The Cat shows up at the house of Sally and her brother one rainy day when their mother is away. Despite the repeated objections of the children's fish, the Cat shows the children a few of his tricks in an attempt to entertain them. In the process he and his companions, Thing One and Thing Two, wreck the house. The children and the fish become more and more alarmed until the Cat produces a machine that he uses to clean everything up and disappears just before the children's mother comes home.
Geisel created the book in response to a debate in the United States about literacy in early childhood and the ineffectiveness of traditional primers such as those featuring Dick and Jane. Geisel was asked to write a more entertaining primer by William Spaulding, whom he had met during World War II and who was then director of the education division at Houghton Mifflin. However, because Geisel was already under contract with Random House, the two publishers agreed to a deal: Houghton Mifflin published the education edition, which was sold to schools, and Random House published the trade edition, which was sold in bookstores.
Geisel gave varying accounts of how he created The Cat in the Hat, but in the version he told most often he was so frustrated with the word list from which he could choose words to write his story that he decided to scan the list and create a story based on the first two words he found that rhymed. The words he found were cat and hat. The book was met with immediate critical and commercial success. Reviewers praised it as an exciting alternative to traditional primers. Three years after its debut, the book had already sold over a million copies, and in 2001 Publishers Weekly listed the book at number nine on its list of best-selling children's books of all time. The book's success led to the creation of Beginner Books, a publishing house centered on producing similar books for young children learning to read. In 1983, Geisel said, "It is the book I'm proudest of because it had something to do with the death of the Dick and Jane primers." The book was adapted into a 1971 animated television special and a 2003 live-action film.Top hat
A top hat, beaver hat, high hat, silk hat, cylinder hat, chimney pot hat or stove pipe hat, sometimes also known by the nickname "topper", is a tall, flat-crowned, broad-brimmed hat, worn by men from the latter part of the 18th to the middle of the 20th century. By the end of World War II, it had become a rarity in ordinary dress, though it continued to be worn in specific instances, such as state funerals, also by those occupying prominent positions in the Bank of England, by certain City stock exchange officials and occasionally when passing between the Law Courts and Lincoln's Inn, London by judges of the Chancery Division and Queen's Counsel.
As of the early 21st century, top hats are still worn at some society events in the UK, notably at church weddings and racing meetings attended by members of the royal family, such as Royal Ascot. They remain part of the formal uniform of certain British institutions, such as the boy-choristers of King's College Choir. They are usually worn with morning dress or white tie, in dressage, and as part of servants' or doormen's livery.
The top hat was frequently associated with the upper class, and was used by satirists and social critics as a symbol of capitalism or the world of business (one current example is the Monopoly Man). The use of the top hat persisted in politics and international diplomacy for many years, including at U.S. presidential inaugurations, the last being worn at the inauguration of John Fitzgerald Kennedy in 1961. The top hat also forms part of the traditional dress of Uncle Sam, a symbol of the United States, generally striped in red, white and blue.
The top hat is also associated with stage magic, both in traditional costume and especially the use of hat tricks. One such trick involving a top hat is the famous "Pulling a Rabbit out of a Hat" trick. Instances of this trick date back to Louis Comte who performed the trick in 1814.Uncertainty principle
In quantum mechanics, the uncertainty principle (also known as Heisenberg's uncertainty principle) is any of a variety of mathematical inequalities asserting a fundamental limit to the precision with which certain pairs of physical properties of a particle, known as complementary variables or canonically conjugate variables such as position x and momentum p, can be known.
Introduced first in 1927, by the German physicist Werner Heisenberg, it states that the more precisely the position of some particle is determined, the less precisely its momentum can be known, and vice versa. The formal inequality relating the standard deviation of position σx and the standard deviation of momentum σp was derived by Earle Hesse Kennard later that year and by Hermann Weyl in 1928:
where ħ is the reduced Planck constant, h/(2π).
Historically, the uncertainty principle has been confused with a somewhat similar effect in physics, called the observer effect, which notes that measurements of certain systems cannot be made without affecting the systems, that is, without changing something in a system. Heisenberg utilized such an observer effect at the quantum level (see below) as a physical "explanation" of quantum uncertainty. It has since become clearer, however, that the uncertainty principle is inherent in the properties of all wave-like systems, and that it arises in quantum mechanics simply due to the matter wave nature of all quantum objects. Thus, the uncertainty principle actually states a fundamental property of quantum systems and is not a statement about the observational success of current technology. It must be emphasized that measurement does not mean only a process in which a physicist-observer takes part, but rather any interaction between classical and quantum objects regardless of any observer.Since the uncertainty principle is such a basic result in quantum mechanics, typical experiments in quantum mechanics routinely observe aspects of it. Certain experiments, however, may deliberately test a particular form of the uncertainty principle as part of their main research program. These include, for example, tests of number–phase uncertainty relations in superconducting or quantum optics systems. Applications dependent on the uncertainty principle for their operation include extremely low-noise technology such as that required in gravitational wave interferometers.