Soccer

Each team consists of a maximum of eleven players (excluding substitutes), one of whom must be the goalkeeper. Competition rules may state a minimum number of players required to constitute a team, which is usually seven. Goalkeepers are the only players allowed to play the ball with their hands or arms, provided they do so within the penalty area in front of their own goal. Though there are a variety of positions in which the outfield (non-goalkeeper) players are strategically placed by a coach, these positions are not defined or required by the Laws.

The basic equipment or kit players are required to wear includes a shirt, shorts, socks, footwear and adequate shin guards. Headgear is not a required piece of basic equipment, but players today may choose to wear it to protect themselves from head injury. Players are forbidden to wear or use anything that is dangerous to themselves or another player, such as jewellery or watches. The goalkeeper must wear clothing that is easily distinguishable from that worn by the other players and the match officials.

A number of players may be replaced by substitutes during the course of the game. The maximum number of substitutions permitted in most competitive international and domestic league games is three, though the permitted number may vary in other competitions or in friendly matches. Common reasons for a substitution include injury, tiredness, ineffectiveness, a tactical switch, or timewasting at the end of a finely poised game. In standard adult matches, a player who has been substituted may not take further part in a match.[28] If any team is unable to field at least seven players due to players being injured or sent-off, the referee will stop the game. The game will be declared as a loss against the team who were unable to field the required number of players.

A game is officiated by a referee, who has "full authority to enforce the Laws of the Game in connection with the match to which he has been appointed" (Law 5), and whose decisions are final. The referee is assisted by two assistant referees. In many high-level games there is also a fourth official who assists the referee and may replace another official should the need arise.

Players, equipment and officials

With the evolution of skateparks and ramp skating, the skateboard began to change. Early skate tricks had consisted mainly of two-dimensional maneuvers like riding on only two wheels ("wheelie" or "manual"), spinning only on the back wheels (a "pivot"), high jumping over a bar and landing on the board again, also known as a "hippie jump", long jumping from one board to another (often over small barrels or fearless teenagers) or slalom.

In 1976, skateboarding was transformed by the invention of the ollie by Alan "Ollie" Gelfand. It remained largely a unique Florida trick until the summer of 1978, when Gelfand made his first visit to California. Gelfand and his revolutionary maneuvers caught the attention of the West Coast skaters and the media where it began to spread worldwide. The ollie was adapted to flat ground by Rodney Mullen in 1982. Mullen also invented the "Magic Flip", which was later renamed the Kickflip, as well many other tricks including, the 360 Kickflip, which is a 360 pop shove it and a kickflip in the same motion. The flat ground ollie allowed skateboarders to perform tricks in mid-air without any more equipment than the skateboard itself, it has formed the basis of many street skating tricks.

For beginners and intermediates, multi-stroke air rifles have been a cost-effective choice as they are generally the cheapest form of air gun available. Several manufacturers make multi-stroke air guns including, to name a few, Sheridan, Benjamin, Daisy, and Crosman. Modified multi-pump guns, with stronger pump linkages and improved valves, can produce muzzle energies in excess of 30 foot-pounds force.

Duration and tie-breaking methods

A standard adult football match consists of two periods of 45 minutes each, known as halves. Each half runs continuously, meaning that the clock is not stopped when the ball is out of play. There is usually a 15-minute half-time break between halves. The end of the match is known as full-time. The referee is the official timekeeper for the match, and may make an allowance for time lost through substitutions, injured players requiring attention, or other stoppages. This added time is commonly referred to as stoppage time or injury time, and is at the sole discretion of the referee. The referee alone signals the end of the match. In matches where a fourth official is appointed, toward the end of the half the referee signals how many minutes of stoppage time he intends to add. The fourth official then informs the players and spectators by holding up a board showing this number. The signalled stoppage time may be further extended by the referee.[35] Added time was introduced because of an incident which happened in 1891 during a match between Stoke and Aston Villa. Trailing 1–0 and with just two minutes remaining, Stoke were awarded a penalty. Villa's goalkeeper kicked the ball out of the ground, and by the time the ball had been recovered, the 90 minutes had elapsed and the game was over.[36] The same law also stands that the duration of either half is extended until the penalty kick to be taken or retaken is completed,[37] thus no game shall end with a penalty to be taken. In league competitions, games may end in a draw, but in some knockout competitions if a game is tied at the end of regulation time it may go into extra time, which consists of two further 15-minute periods. If the score is still tied after extra time, some competitions allow the use of penalty shootouts (known officially in the Laws of the Game as "kicks from the penalty mark") to determine which team will progress to the next stage of the tournament. Goals scored during extra time periods count toward the final score of the game, but kicks from the penalty mark are only used to decide the team that progresses to the next part of the tournament (with goals scored in a penalty shootout not making up part of the final score). In competitions using two-legged matches, each team competes at home once, with an aggregate score from the two matches deciding which team progresses. Where aggregates are equal, the away goals rule may be used to determine the winners, in which case the winner is the team that scored the most goals in the leg played away from home. If the result is still equal, kicks from the penalty mark are usually required, though some competitions may require a tied game to be replayed. In the late 1990s and early 2000s, the IFAB experimented with ways of creating a winner without requiring a penalty shootout, which was often seen as an undesirable way to end a match. These involved rules ending a game in extra time early, either when the first goal in extra time was scored (golden goal), or if one team held a lead at the end of the first period of extra time (silver goal). Golden goal was used at the World Cup in 1998 and 2002. The first World Cup game decided by a golden goal was France's victory over Paraguay in 1998. Germany was the first nation to score a golden goal in a major competition, beating Czech Republic in the final of Euro 1996. Silver goal was used in Euro 2004. Both these experiments have been discontinued by IFAB.

International competitions

The major international competition in football is the World Cup, organised by FIFA. This competition takes place over a four-year period. More than 190 national teams compete in qualifying tournaments within the scope of continental confederations for a place in the finals. The finals tournament, which is held every four years, involves 32 national teams competing over a four-week period.[44] The 2006 FIFA World Cup took place in Germany; in 2010 it will be held in South Africa.[45] There has been a football tournament at every Summer Olympic Games since 1900, except at the 1932 games in Los Angeles. Before the inception of the World Cup, the Olympics (especially during the 1920s) had the same status as the World Cup. Originally, the event was for amateurs only,[16] however, since the 1984 Summer Olympics professional players have been permitted, albeit with certain restrictions which prevent countries from fielding their strongest sides. Currently, the Olympic men's tournament is played at Under-23 level. In the past the Olympics have allowed a restricted number of over-age players per team;[46] but that practice ceased in the 2008 Olympics. The Olympic competition is not generally considered to carry the same international significance and prestige as the World Cup. A women's tournament was added in 1996; in contrast to the men's event, full international sides without age restrictions play the women’s Olympic tournament. It thus carries international prestige considered comparable to that of the FIFA Women's World Cup. After the World Cup, the most important international football competitions are the continental championships, which are organised by each continental confederation and contested between national teams. These are the European Championship (UEFA), the Copa América (CONMEBOL), African Cup of Nations (CAF), the Asian Cup (AFC), the CONCACAF Gold Cup (CONCACAF) and the OFC Nations Cup (OFC). The FIFA Confederations Cup is contested by the winners of all 6 continental championships, the current FIFA World Cup champions and the country which is hosting the Confederations Cup. This is generally regarded as a warm up tournament for the upcoming FIFA World Cup and does not carry the same prestige as the World Cup itself. The most prestigious competitions in club football are the respective continental championships, which are generally contested between national champions, for example the UEFA Champions League in Europe and the Copa Libertadores de América in South America. The winners of each continental competition contest the FIFA Club World Cup.