In several team sports, matches are played in two halves. Half-time (also written halftime or half time) is the name given to the interval between the two halves of the match. Typically, after half-time, teams swap ends of the field of play in order to reduce any advantage that may be gained from wind or a slope to the playing surface, for example. While it exists mainly to allow competitors to rest briefly and recover from the play of the first half, half-time also serves a number of other purposes. It also serves as an intermission for spectators, and it often features entertainment, such as cheerleading performances, tifos, performances by school marching bands (particularly in high school and collegiate sports in North America), or concerts featuring popular music acts (particularly in major events such as the Super Bowl). On games that are broadcast on television and radio, it also provides broadcasters with an opportunity to give a recap of the first half of the game, air highlights of other games in progress, air commercials and other advertisements, provide analysis on the game, or air game-related festivities (such as an aforementioned half-time performance). In the NFL (National Football League) half-time is 12 minutes, although for major events like the Super Bowl it may last longer to allow for more activities like musical performances. History The origin of changing ends at half-time lies in the early English public school football games. One early use of a fixed half-time, and it is suggested the origin of the practice, was to allow for two football teams each used to a different set of rules to play half of the game by familiar rules, and half by the opposition rules. This was practised notably between followers of Eton-rules football (closer to modern association football) and Rugby-rules football (closer to modern rugby Rugby union). This use of half-time was unnecessary after the standardisation of football rules in 1863 (see Laws of the Game) but is still used for the now-rare contests between teams playing different codes of football. Changing ends at half-time (if no goals had been scored) was part of the following schools' codes: Brighton, Eton, Rossall, Sheffield, and Winchester. Other schools changed every time that side scored (Cheltenham, FA, Harrow, Marlborough, Rugby, Shrewsbury, Uppingham schools) The 1863 Cambridge Rules state: "In a match when half the time agreed upon has elapsed, the side shall