What is a Chess Puzzle ?

This article is an extract from the chess website bestofchess.com.... you can read the full article by clicking on the link below. A chess puzzle is a puzzle in which knowledge of  rules and of the pieces  of chess is used to solve a chess-related problem logically. The longstanding popularity of chess has paved the way for a rich tradition of such chess-related puzzles and composed problems, which assume a familiarity with the pieces and rules of chess, but can set different objectives than a standard game.
Some chess puzzles may derive from studies which were intended to help a student of the game learn how to seal a victory, but have since evolved into an entirely separate art.

Chess puzzles are usally in form of chess problems or tactical puzzles.

Orthodox chess problems involve positions that can arise from actual game play. The most common orthodox chess puzzle takes the form of checkmate in n moves. The puzzle positions are seldom similar to positions from actual play, and the challenge is not to find a winning move, but rather to find the (usually unique) move which forces checkmate as rapidly as possible. Heterodox chess problems involve conditions that are impossible with normal play, such as multiple kings or chess variants, while fairy chess problems employ pieces not used in orthodox chess, such as the amazon (a piece combining the powers of the queen and the knight).