Traditionally, chess puzzles have been published in newspapers, and you'll even find compilations of them in books. Today, Web sites offer chess puzzles for the casual beginner, intermediate or advanced player to stretch his or her mental muscles.
The most common puzzles, directmates, ask an individual to win in a certain number of moves. Two-movers require you to win in two moves, three-movers require a win in three moves, and those that require more moves are called more-movers. A well-composed puzzle of this kind will only have one possible solution in the expressed number of moves. It will also be a foolproof solution that assumes the other side will play its best defense.