Alan Kay

Alan Curtis Kay (born May 17, 1940[1]) is an American computer scientist. He has been elected a Fellow of the American Academy of Arts and Sciences, the National Academy of Engineering, and the Royal Society of Arts.[2] He is best known for his pioneering work on object-oriented programming and windowing graphical user interface design.

He is the president of the Viewpoints Research Institute, and an adjunct professor of computer science at the University of California, Los Angeles. He is also on the advisory board of TTI/Vanguard. Until mid-2005, he was a senior fellow at HP Labs, a visiting professor at Kyoto University, and an adjunct professor at the Massachusetts Institute of Technology (MIT).[3]

Kay is also a former professional jazz guitarist, composer, and theatrical designer, and an amateur classical pipe organist.

Alan Kay
Alan Kay (3097597186)
Kay at the 2008 40th anniversary of The Mother of All Demos
Alan Curtis Kay

May 17, 1940 (age 78)
CitizenshipUnited States
Alma materUniversity of Colorado at Boulder
University of Utah
Known forDynabook
object-oriented programming
graphical user interface windows
Spouse(s)Bonnie MacBird
AwardsACM Turing Award (2003)
Kyoto Prize
Charles Stark Draper Prize
Scientific career
FieldsComputer science
InstitutionsXerox PARC
Stanford University
Atari Inc.
Apple Inc. ATG
Walt Disney Imagineering
Kyoto University
Viewpoints Research Institute
Hewlett-Packard Labs
Doctoral advisor

Early life and work

In an interview on education in America with the Davis Group Ltd., Kay said,

I had the fortune or misfortune to learn how to read fluently starting at the age of three. So I had read maybe 150 books by the time I hit 1st grade. And I already knew that the teachers were lying to me.[4]

Originally from Springfield, Massachusetts, Kay's family relocated several times due to his father's career in physiology before ultimately settling in the New York metropolitan area when he was nine.

He attended the prestigious Brooklyn Technical High School, where he was suspended due to insubordination in his senior year. Having already accumulated enough credits to graduate, Kay then attended Bethany College in Bethany, West Virginia. He majored in biology and minored in mathematics before he was asked to leave by the administration for protesting the institution's Jewish quota.

Thereafter, Kay taught guitar in Denver, Colorado for a year and hastily enlisted in the United States Air Force when the local draft board inquired about his nonstudent status. Assigned as a computer programmer (a rare billet dominated by women due to the secretarial connotations of the field in the era) after passing an aptitude test, he devised an early cross-platform file transfer system.

Following his discharge, Kay enrolled at the University of Colorado Boulder, earning a bachelor's degree in mathematics and molecular biology in 1966. Before and during this time, he worked as a professional jazz guitarist. During his studies at CU, he wrote the music for an adaptation of The Hobbit and other campus theatricals.

In the autumn of 1966, he began graduate school at the University of Utah College of Engineering. He earned an M.S. in electrical engineering in 1968 before taking his Ph.D. in computer science in 1969. His doctoral dissertation, FLEX: A Flexible Extendable Language, described the invention of a computer language known as FLEX.[5][6][7] While at Utah, he worked with "father of computer graphics" Ivan Sutherland, best known for writing such pioneering programs as Sketchpad. This greatly inspired Kay's evolving views on objects and programming. As he grew busier with ARPA research, he ended his musical career.

In 1968, he met Seymour Papert and learned of the Logo programming language, a dialect of Lisp optimized for educational purposes. This led him to learn of the work of Jean Piaget, Jerome Bruner, Lev Vygotsky, and of constructionist learning, further influencing his professional orientation.

Leaving Utah as an associate professor of computer science in 1969, Kay became a visiting researcher at the Stanford Artificial Intelligence Laboratory in anticipation of accepting a professorship at Carnegie Mellon University. Instead, in 1970, he joined the Xerox PARC research staff in Palo Alto, California. Throughout the decade, he developed prototypes of networked workstations using the programming language Smalltalk. These inventions were later commercialized by Apple in their Lisa and Macintosh computers.

Kay is one of the fathers of the idea of object-oriented programming, which he named, along with some colleagues at PARC. Some of the original object-oriented concepts, including the use of the words 'object' and 'class', had been developed for Simula 67 at the Norwegian Computing Center. Later he said:

I'm sorry that I long ago coined the term "objects" for this topic because it gets many people to focus on the lesser idea. The big idea is "messaging"[8]

While at PARC, Kay conceived the Dynabook concept, a key progenitor of laptop and tablet computers and the e-book. He is also the architect of the modern overlapping windowing graphical user interface (GUI).[9] Because the Dynabook was conceived as an educational platform, Kay is considered to be one of the first researchers into mobile learning; many features of the Dynabook concept have been adopted in the design of the One Laptop Per Child educational platform, with which Kay is actively involved.

The field of computing is awaiting new revolution to happen, according to Kay, in which educational communities, parents, and children will not see in it a set of tools invented by Douglas Engelbart, but a medium in the Marshall McLuhan sense. He wrote:

As with Simulas leading to OOP, this encounter finally hit me with what the destiny of personal computing really was going to be. Not a personal dynamic vehicle, as in Engelbart's metaphor opposed to the IBM "railroads", but something much more profound: a personal dynamic medium. With a vehicle one could wait until high school and give "drivers ed", but if it was a medium, it had to extend into the world of childhood.[10]

Recent work and recognition

From 1981 to 1984, Kay was Atari's Chief Scientist. He became an Apple Fellow in 1984. Following the closure of the company's Advanced Technology Group in 1997,[11] he was recruited by his friend Bran Ferren, head of research and development at Disney, to join Walt Disney Imagineering as a Disney Fellow. He remained there until Ferren left to start Applied Minds Inc with Imagineer Danny Hillis, leading to the cessation of the Fellows program. In 2001, he founded Viewpoints Research Institute, a non-profit organization dedicated to children, learning, and advanced software development. For its first ten years, Kay and his Viewpoints group were based at Applied Minds in Glendale, California, where he and Ferren continued to work together on various projects. Kay was also a Senior Fellow at Hewlett-Packard until HP disbanded the Advanced Software Research Team on July 20, 2005.

Kay taught a Fall 2011 class, "Powerful Ideas: Useful Tools to Understand the World", at New York University's Interactive Telecommunications Program (ITP) along with full-time ITP faculty member Nancy Hechinger. The goal of the class was to devise new forms of teaching/learning based on fundamental, powerful concepts rather than traditional rote learning.[12]

Squeak, Etoys, and Croquet

In December 1995, while still at Apple, Kay collaborated with many others to start the open source Squeak version of Smalltalk, and he continues to work on it. As part of this effort, in November 1996, his team began research on what became the Etoys system. More recently he started, along with David A. Smith, David P. Reed, Andreas Raab, Rick McGeer, Julian Lombardi and Mark McCahill, the Croquet Project, an open source networked 2D and 3D environment for collaborative work.


In 2001, it became clear that the Etoy architecture in Squeak had reached its limits in what the Morphic interface infrastructure could do. Andreas Raab was a researcher working in Kay's group, then at Hewlett-Packard. He proposed defining a "script process" and providing a default scheduling mechanism that avoids several more general problems.[13] The result was a new user interface, proposed to replace the Squeak Morphic user interface in the future. Tweak added mechanisms of islands, asynchronous messaging, players and costumes, language extensions, projects, and tile scripting.[14] Its underlying object system is class-based, but to users (during programming) it acts like it is prototype-based. Tweak objects are created and run in Tweak project windows.

Children's Machine

In November 2005, at the World Summit on the Information Society, the MIT research laboratories unveiled a new laptop computer, for educational use around the world. It has many names: the $100 Laptop, the One Laptop per Child program, the Children's Machine, and the XO-1. The program was begun and is sustained by Kay's friend, Nicholas Negroponte, and is based on Kay's Dynabook ideal. Kay is a prominent co-developer of the computer, focusing on its educational software using Squeak and Etoys.

Reinventing programming

Kay has lectured extensively on the idea that the computer revolution is very new, and all of the good ideas have not been universally implemented. Lectures at OOPSLA 1997 conference and his ACM Turing award talk, entitled "The Computer Revolution Hasn't Happened Yet" were informed by his experiences with Sketchpad, Simula, Smalltalk, and the bloated code of commercial software.

On August 31, 2006, Kay's proposal to the United States National Science Foundation (NSF) was granted, thus funding Viewpoints Research Institute for several years. The proposal title was: STEPS Toward the Reinvention of Programming: A compact and Practical Model of Personal Computing as a Self-exploratorium.[15] A sense of what Kay is trying to do comes from this quote, from the abstract of a seminar on this given at Intel Research Labs, Berkeley: "The conglomeration of commercial and most open source software consumes in the neighborhood of several hundreds of millions of lines of code these days. We wonder: how small could be an understandable practical "Model T" design that covers this functionality? 1M lines of code? 200K LOC? 100K LOC? 20K LOC?"[16]

Awards and honors

Alan Kay has received many awards and honors. Among them:

His other honors include the J-D Warnier Prix d'Informatique, the ACM Systems Software Award, the NEC Computers & Communication Foundation Prize, the Funai Foundation Prize, the Lewis Branscomb Technology Award, and the ACM SIGCSE Award for Outstanding Contributions to Computer Science Education.

See also


  1. ^ a b "ACM Turing Award". 2003. published by the Association for Computing Machinery 2012
  2. ^ Alan Kay (1997). The Computer Revolution Hasn't Happened Yet (Speech).
  3. ^ Paczkowski, John (21 July 2005). "HP converting storied garage into recycling center". Good Morning Silicon Valley. Media News Group. Archived from the original on 2007-06-26.
  4. ^ "Interview with Alan Kay on education". The Generational Divide. The Davis Group. Retrieved 5 March 2011.
  5. ^ Alan C. Kay (1968). "FLEX: A Flexible Extendable Language" (PDF). University of Utah.
  6. ^ H. Peter Alesso; C.F. Smith (2008). Connections: Patterns of Discovery. Wiley Series on Systems Engineering and Analysis, 29. John Wiley & Sons. p. 61. ISBN 978-0-470-11881-8. Retrieved 2015-08-15.
  7. ^ S.B. Barnes. "Alan Kay: Transforming the Computer Into a Communication Medium" (PDF). Engineering & Technology History Wiki. Archived from the original (PDF) on 1 July 2016.
  8. ^ "AlanKayOnMessaging".
  9. ^ Bergin, Jr., Thomas J.; Gibson, Jr., Richard G. (1996). History of Programming Languages II. New York, NY: ACM Press, Addison-Wesley.
  10. ^ "The Early History of Smalltalk". Retrieved 2016-12-16.
  11. ^ "Alan Kay". I Programmer. 13 November 2009.
  12. ^ Kay, Alan (2011-09-15). "Powerful Ideas: Useful Tools to Understand the World". Retrieved 2011-09-15.
  13. ^ Andreas Raab (6 July 2001). "Events, Scripts & Multiple Processes". Archived from the original on 2 October 2011. Retrieved 2009-06-07.
  14. ^ "Tweak: Whitepapers". Archived from the original on 2 October 2011.
  15. ^ Alan Kay; Dan Ingalls; Yoshiki Ohshima; Ian Piumarta; Andreas Raab. "Steps Toward The Reinvention of Programming – A Compact And Practical Model of Personal Computing As A Self-Exploratorium" (PDF). Archived from the original (PDF) on 2013-05-08. Retrieved 2013-03-23. Proposal to NSF – Granted on August 31st 2006
  16. ^ Kay, Alan (2006-11-27). "How Simply and Understandably Could The "Personal Computing Experience" Be Programmed?". Archived from the original on 2007-06-25.
  17. ^ "UdK 01-Award". Archived from the original on 2005-05-28.
  18. ^ "2004 Recipients of the Charles Stark Draper Prize". National Academy of Engineering. National Academy of Sciences.
  19. ^ "Hedersdoktorer 2008-1995, inklusive ämnesområden" (in Swedish). KTH. Archived from the original on 2009-01-09. Retrieved 2009-06-07.
  20. ^ "Tech forms dual-degree program with Chinese university" (PDF). The Whistle. Georgia Institute of Technology. 19 December 2005. Archived from the original (PDF) on 1 July 2016.
  21. ^ "Columbia College Chicago Announces 2005 Commencement Ceremonies". Columbia College Chicago. 10 May 2005. Archived from the original on 2012-03-20.
  22. ^ "UW's convocation graduates 4,378 students, awards 10 honorary degrees". University of Waterloo. 2008-06-10. Retrieved 2009-06-07.
  23. ^ "Alan Curtis Kay: Doctor Honoris Causa". Facultad de Informática, Universidad de Murcia. 2010.
  24. ^ "Alan Kay receives an honorary degree from the School of Informatics". School of Informatics, University of Edinburgh. 2017.
  25. ^ "Alan Kay: 1999 Fellow Awards Recipient". Computer History Museum. Archived from the original on 2012-10-03.
  26. ^ "ACM Fellows". Association of Computing Machinery. 2008.
  27. ^ "Alan Kay as HPI fellow appreciated" (in German). 21 July 2011. Archived from the original on 24 July 2011.
  28. ^ Kay, Alan (21 July 2011). "Programming and Scaling". Germany, Potsdam, Hasso-Plattner Institute: HPI Potsdam.

External links


Aida/Web is an object-oriented, open source Smalltalk web application server using the model-view-controller (MVC) architectural pattern.

Adele Goldberg (computer scientist)

Adele Goldberg (born July 7, 1945) is a computer scientist who participated in developing the programming language Smalltalk-80 and various concepts related to object-oriented programming while a researcher at the Xerox Palo Alto Research Center (PARC), in the 1970s.

Alan Kay (disambiguation)

Alan Kay is a computer scientist known for his work at the Xerox Palo Alto Research Center.

Alan Kay may also refer to:

Alan Kay (judge), US magistrate judge in Washington DC

Alan Cooke Kay (born 1932), judge on the United States District Court for the District of Hawaii

Alan Kay (footballer) (born 1961), Scottish footballer

Alan Kay, season 1 winner of the TV series Alone

Alan Kay (footballer)

Alan Kay (born 2 August 1961) was a Scottish footballer who played for Partick Thistle and Dumbarton.

Alan Kay (judge)

Alan Kay is a United States Magistrate Judge for the United States District Court for the District of Columbia.

Apple Advanced Technology Group

The Advanced Technology Group (ATG) was a corporate research laboratory at Apple Computer from 1986 to 1997. ATG was an evolution of Apple's Education Research Group (ERG) and was started by Larry Tesler in October 1986 to study long term research into future technologies that were beyond the time frame or organizational scope of any individual product group. Over the next decade, it was led by David Nagel, Richard LeFaivre, and Donald Norman. It was known as Apple Research Labs during Norman's tenure as VP of the organization. Steve Jobs closed the group when he returned to Apple in 1997.ATG had research efforts in both hardware and software, with groups focused on such areas as Human-Computer Interaction, Speech Recognition, Educational Technology, Networking, Information Access, Distributed Operating systems, Collaborative Computing, Computer Graphics, and Language/action perspective. Many of these efforts are described in a special issue of the ACM SIGCHI Bulletin which provided a retrospective of the ATG work after the lab was shut down. ATG was also home to four Apple Fellows: Al Alcorn, object-oriented software pioneer; Alan Kay; Bill Atkinson; and laser printer inventor Gary Starkweather. Further, ATG funded university research and, starting in 1992, held an annual design competition for teams of students.

Apple's ATG was the birthplace of Color QuickDraw, QuickTime, QuickTime VR, QuickDraw 3D, QuickRing, 3DMF the 3D metafile graphics format, ColorSync, HyperCard, Apple events, AppleScript, Apple's PlainTalk speech recognition software, Apple Data Detectors, the V-Twin software for indexing, storing, and searching text documents, Macintalk Pro Speech Synthesis, the Newton handwriting recognizer, the component software technology leading to OpenDoc, MCF, HotSauce, Squeak, and the children's programming environment Cocoa (a trademark Apple later reused for its otherwise unrelated Cocoa application frameworks).

Bonnie MacBird

Bonnie MacBird is a writer, actress, playwright, screenwriter and producer known as the original writer of the science fiction film Tron.

MacBird is a native of San Francisco, California and graduated from Stanford University with a bachelor's degree in music and a master's degree in film. She is married to computer-scientist Alan Kay.

Buckminster Fuller Challenge

The Buckminster Fuller Challenge is an annual international design competition that awards $100,000 to the most comprehensive solution to a pressing global problem. The Challenge was launched in 2007 and is a program of The Buckminster Fuller Institute. The competition, open to designers, artists, architects, students, environmentalists, and organizations world-wide, has been dubbed "Socially-Responsible Design's Highest Award" by Metropolis Magazine.According to the Buckminster Fuller Challenge website: "Winning solutions are regionally specific yet globally applicable and present a truly comprehensive, anticipatory, integrated approach to solving the world's complex problems." Furthermore, the criteria of the Challenge calls not for a stand-alone solution, but an integrated strategy that addresses social, environmental, economic and cultural issues. This is aligned with the design approach of Buckminster Fuller, which he referred to as "comprehensive anticipatory design science".Winners of the Buckminster Fuller Challenge include John Todd (2008), MIT's Smart Cities Group (2009),

, Allan Savory and the Africa Center for Holistic management (2010), Blue Ventures (2011) and the Living Building Challenge (2012).Each year's winner is ultimately decided by an international jury of renowned whole systems thinkers and practitioners of sustainability. Former jury members include Jose Zaglul, Alan Kay, Mitchell Joachim, Adam Bly, Jamais Cascio, Nicholas Grimshaw, Hunter Lovins, William McDonough, Janine Benyus, and Danny Hillis.

Although there is only one winner per year, the majority of the entries received are featured on the Buckminster Fuller Challenge website within a fully searchable database known as the Idea Index.

Croquet Project

The Croquet Project was a software project intended to promote the continued development of the Croquet open-source software development kit to create and deliver collaborative multi-user online applications.

Implemented in Squeak Smalltalk, Croquet supports communication, collaboration, resource sharing, and synchronous computation among multiple users. Applications created with the Croquet software development kit (SDK) can be used to support highly scalable collaborative data visualization, virtual learning and problem solving environments, 3D wikis, online gaming environments (massively multiplayer online role-playing games (MMORPGs)), and privately maintained or interconnected multiuser virtual environments.

Since release of the Croquet SDK in 2007, the SDK has not been under active development. All further development of the technology has occurred under the Open Cobalt effort.

Dan Ingalls

Daniel Henry Holmes Ingalls Jr. (born 1944) is a pioneer of object-oriented computer programming and the principal architect, designer and implementer of five generations of Smalltalk environments. He designed the bytecoded virtual machine that made Smalltalk practical in 1976. He also invented bit blit, the general-purpose graphical operation that underlies most bitmap graphics systems today, and pop-up menus. He designed the generalizations of BitBlt to arbitrary color depth, with built-in scaling, rotation, and anti-aliasing. His major contributions to the Squeak system include the original concept of a Smalltalk written in itself and made portable and efficient by a Smalltalk-to-C translator.

David P. Reed

David Patrick Reed (born January 31, 1952) is an American computer scientist, educated at the Massachusetts Institute of Technology, known for a number of significant contributions to computer networking and wireless communications networks.

He was involved in the early development of TCP/IP, and was the designer of the User Datagram Protocol (UDP), though he finds this title "a little embarrassing". He was also one of the authors of the original paper about the end-to-end principle, End-to-end arguments in system design, published in 1984.

He is also known for Reed's law, his assertion that the utility of large networks, particularly social networks, can scale exponentially with the size of the network. (It was first cited in "The Law of the Pack," Harvard Business Review (February 2001) pp 23–4.)

From 2003–2010, Reed was an adjunct professor at the MIT Media Lab, where he co-led the Viral Communications group and the Communication Futures program. He currently serves as a senior vice president of the Chief Scientist Group at SAP Labs.He is one of six principal architects of the Croquet project (along with Alan Kay, Julian Lombardi, Andreas Raab, David A. Smith, and Mark McCahill). He is also on the advisory board of TTI/Vanguard.

The 1978 dissertation by David P. Reed which quite clearly describes Multiversion concurrency control (MVCC) and claims it as an original work. MVCC is a concurrency control method commonly used by database management systems to provide concurrent access to the database and in programming languages to implement transactional memory.


The KiddiComp concept, envisioned by Alan Kay in 1968 while a PhD candidate, and later developed and described as the Dynabook in his 1972 proposal "A personal computer for children of all ages", outlines the requirements for a conceptual portable educational device that would offer similar functionality to that now supplied via a laptop computer or (in some of its other incarnations) a tablet or slate computer with the exception of the requirement for any Dynabook device offering near eternal battery life. Adults could also use a Dynabook, but the target audience was children.

Part of the motivation and funding for the Dynabook project came from the need for portable military maintenance, repair, and operations documentation. Eliminating the need to move large amounts of difficult-to-access paper in a dynamic military theatre provided significant US Department of Defense funding.

Though the hardware required to create a Dynabook is here today, Alan Kay still thinks the Dynabook hasn't been invented yet, because key software and educational curricula are missing. When Microsoft came up with its tablet PC, Kay was quoted as saying "Microsoft's Tablet PC, the first Dynabook-like computer good enough to criticize".Toshiba also has a line of sub-notebook computers called DynaBooks. In June 2018, Sharp acquired a majority stake in Toshiba's PC business including laptops and tablets sold under the Dynabook brand.

Etoys (programming language)

Etoys is a child-friendly computer environment and object-oriented prototype-based programming language for use in education.

Etoys is a media-rich authoring environment with a scripted object model for many different objects that runs on different platforms and is free and open source.

Flex (language)

In computing, the FLEX language was developed by Alan Kay in the late 1960s while exploring ideas that would later evolve into the Smalltalk programming language.

Robert S. Barton

Robert Stanley "Bob" Barton (February 13, 1925 – January 28, 2009) was recognized as the chief architect of the Burroughs B5000 and other computers such as the B1700, and a co-inventor of dataflow. Barton's thinking has been broadly influential. As one example, Barton influenced the systems and higher-level computer language thinking of Alan Kay who went on to further develop object-oriented programming, co-design Smalltalk, and develop concepts key to modern GUI systems built into the Macintosh and later Microsoft Windows.

Barton designed machines at a more abstract level, not tied to the technology constraints of the time. He employed high-level languages and a stack machine in his design of the Burroughs Corporation B5000 computer. Barton's B5000 design survives in the modern Unisys Burroughs MCP. His work with stack architectures was the first implementation in a mainframe computer. Hewlett-Packard would later use the stack architecture in its HP 3000 computers, and in HP calculators with Reverse Polish Notation (RPN).

Barton died on January 28, 2009, in Portland, Oregon, at the age of 83.

Robert Stein (computer pioneer)

Robert Stein (born April 20, 1946) founded The Voyager Company in 1985, the first commercial multimedia CD-ROM publisher, and The Criterion Collection, a collection of definitive films on digital media with in-depth background information (including the first films with recorded audio commentary).

Born and raised in New York City, Stein attended Columbia University, majoring in psychology. Later, he earned a master's degree in education from Harvard University.

Stein then worked with Alan Kay at the Atari Research Group on various electronic publishing projects.

After Voyager, Stein founded Night Kitchen to develop authoring tools for experimental electronic publishing, primarily TK3.

Stein is the director of the Institute for the Future of the Book. According to Stein: "The Institute has two principal activities. One is building high-end tools for making complex electronic documents (part of the Mellon Foundation's higher-ed digital infrastructure initiative). The other is exploring and hopefully influencing the evolution of new forms of intellectual expression and discourse." This new scholarly direction is being explored under the umbrella of MediaCommons.


Smalltalk is an object-oriented, dynamically typed reflective programming language. Smalltalk was created as the language in underpinning the "new world" of computing exemplified by "human–computer symbiosis". It was designed and created in part for educational use, more so for constructionist learning, at the Learning Research Group (LRG) of Xerox PARC by Alan Kay, Dan Ingalls, Adele Goldberg, Ted Kaehler, Scott Wallace, and others during the 1970s.

The language was first generally released as Smalltalk-80. Smalltalk-like languages are in continuing active development and have gathered loyal communities of users around them. ANSI Smalltalk was ratified in 1998 and represents the standard version of Smalltalk.Smalltalk took second place for "most loved programming language" in the Stack Overflow Developer Survey in 2017, but it was not among the 26 most loved programming languages of the 2018 survey.

The Art of the Metaobject Protocol

The Art of the Metaobject Protocol (AMOP) is a 1991 book by Gregor Kiczales, Jim des Rivieres, and Daniel G. Bobrow (all three working for Xerox PARC) on the subject of metaobject protocol.

Y Combinator

Y Combinator is an American seed accelerator, started in March 2005. Y Combinator has spawned a number of highly successful companies and is consistently ranked at the top of U.S. accelerators.

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.