In addition to the basic rules each chess piece has, there are also special moves that can factor into game development and outcome. Though they may seem complicated at first, once a player becomes more familiar with overall play, when to use these special moves will become clearer as well.
Indeed, by simply looking at a chess board and its current state, an experienced player should be able to determine whether or not a special move is needed or not. Held in reserve, these special moves are only used when the game demands it. However, at some point in a match, one (or more) is likely to be called upon.
And just what are these moves found within a chess set? In short, theyre: castling, en passant, and pawn promotion.
During the course of play, it may become necessary for a king to move quickly. Since the piece can only move one square at a time though, this is easier said than done. Thankfully, theres castling, wherein the king can receive shelter by working with a rook.
Basically, castling permits the king to move two squares on the chess board, to either the right or left. The rook (still in its corner) in which the king moves toward is then permitted to slide around the king, to its other side. Visually, the rook protects the king on the weak side, pushing the king to safety behind a wall.
There are a few conditions: 1) the rook and king cannot have moved yet on the board and then returned to their respective positions. If one of the participating chess pieces moves, castling is disallowed; and 2) the path between the king and rook must be cleared. The special move is the only one in which two pieces can move, but only two pieces can move. No other piece can be involved.
Referred to by some as the soul of chess, pawns are far more important than their lowly status within a chess set might suggest. In fact, these puny (yet powerful) pawns have two special moves all to themselves, both of which can factor greatly into defense, strategy, and board-space control.
The first of these special moves is en passant, which is a capture move available to a pawn only on its fifth rank. As a general rule, pawns may move one or two squares forward upon first move. Afterwards, only one. If a pawn tries to avoid capture by an opposing pawn by moving two squares forward (instead of one), then the rival pawn has the option to use en passant on the very next move: meaning, it can move diagonally one square and take the defending pawn anyway, as if the pawn had only moved one square to start.
This move can be used multiple times during a game, but only from the fifth rank and it must be made immediately after one pawn attempts to avoid capture. If the opposing player moves another chess piece, en passant (for this particular pawn) is no longer in play.
And finally, pawns are the only pieces of a chess set up for a promotion. If a pawn manages to move to the eight rank, then it can be promoted to any other piece. Often exchanged for a queen, this transformative power can turn the chess boards weakest piece into its most powerful. The only piece the pawn cannot be promoted to is king.