A drinking game is one played in which the goal is for you or your opponents to become intoxicated, through quantified or qualified measures. Some drinking games have an element of strategy, while others simply have none whatsoever, and there is no way to increase or decrease your chance of becoming intoxicated.
Some drinking games are best played between small numbers of people while others are "party" games where multiple people are best suited. With many drinking games the amount, and sometimes the type, of alcohol is very specific to the game. For example, "Beer Pong" is a game played usually with two teams of two on the opposite ends of a long table, with a series of cups filled with beer that they must consume or make their opponents consume throughout the course of the game. Another game, "Quarters" usually involves a player's ability to bounce a quarter off of a surface and into a shot glass.
Part of the philosophy behind a drinking game is assist in the breaking down of social barriers between participants: the implied fun, coupled with the challenge and sometimes sportsmanship may build a camaraderie between players. However, these factors may also involve serious risks because the element of the game can surpass any concern for personal health or safety (alcohol poisoning, death, etc.)