In gambling there are two basic types of game: games of chance and games of skill.
Games of chance include:
craps, roulette, slot machines, keno, bingo and lotteries.
These are considered games of chance because each event is separate, with no relationship to the preceding or succeeding event. They require no skill on the part of the player and depend totally on lady luck.
Games of skill include:
blackjack, baccarat, video poker, poker, sports and horse racing.
These are considered games of skill because preceding events do affect what will happen next. By playing these games cleverly you can greatly increase your chances of winning.
See: Undestanding probability ( Probabilities, left menu )