The penalty flag (or just "flag") is a yellow cloth used in several field sports including American football and lacrosse by game officials to identify and sometimes mark the location of penalties or infractions that occur during regular play. It is usually wrapped around a weight, such as sand or beans so it can be thrown accurately over greater distances. Many officials previously weighted flags with ball bearings, but the practice was largely discontinued after a flag thrown by NFL referee Jeff Triplette struck Cleveland Browns offensive tackle Orlando Brown Sr. in the eye during a 1999 game vs. the Jacksonville Jaguars, causing a serious injury to Brown, who later attacked Triplette and threw him to the ground. Brown was forced to sit out three seasons because of the eye injury and settled with the NFL for a reported amount of $25 million.
The flag is colored orange in Canadian football. NFL penalty flags were colored white until 1965, when the color was changed to yellow. Penalty flags in college football were red until the 1970s.
The idea for the penalty flag came from Youngstown State coach Dwight Beede and first used in a game against Oklahoma City University on October 17, 1941. Prior to the use of flags, officials used horns and whistles to signal a penalty. Official adoption of the use of the flag occurred at the 1948 American Football Coaches rules session. The National Football League first used flags on September 17, 1948 when the Green Bay Packers played the Boston Yanks.
In some football leagues, coaches are given a challenge flag of similar construction as a penalty flag. The flag is red in American football and yellow in Canadian football, so it contrasts with the officials' penalty flags. This is thrown by a coach when he wishes to contest (challenge) a referee's decision.