Paintball is any one of several game variations where two or more players attempt to "mark" each other by firing "paintballs" at each other from a "paintball marker" (gun). A player is marked if a paintball contacts, bursts and sheds its colored fill on him or his marker. A typical rule of thumb is that the splatter should be contiguous over an area the size of a quarter but not all fields use this. "Bouncers" don't count as hits in a game. Bouncers are hits that do not bust on the player. In other instances, people also play by being hit more than once in a game and keep playing. Referees are also in the sport like any other to enforce the rules and ensure safety for players of all ages. They are also there to make sure that no one is violating the rules and to check players on the field for hits. Violaters are usually thrown from the game.
In addition to paintballs and markers, players also need a "hopper" to hold their paintballs (this also includes the use of an agitating hopper that feeds the marker faster for a steady rate of fire) and an air source (like a bottle of carbon dioxide) to propel the paintball from the marker. Nitrogen or High Pressure Air can also be used to propel the ball. These are also held in a bottle-like container. These air sources are primarily used by people who play often and have tournament-grade markers.
Players must don a paintball mask and goggles (preferrably goggles with "thermal lenses" to avoid fogging) to avoid serious injury to the face, ears, and eyes. Regulated fields require masks, goggles and marker plugs or barrel covers to play on the field. The plugs and covers are used to prevent accidental firing of a paintball while not engaged in a game. Paintballs travel about 280 feet per second and getting hit with a paintball usually stings and leaves a welt or bruise on the skin. In general, getting hit by a paintball from far away hurts less then getting hit at close range. Also, getting hit can hurt more if the ball does not break, and instead bounces.
Players usually fall into two categories: recreational and tournament players. Tournament players take the game seriously, investing perhaps $2,000 in paintball gear. A top of the line paintball marker can cost $1,500 - $2,000. A recreational marker can however be purchased for $100 to $300.