Chess has been called the game of kings. The ultimate object of chess is to capture the opponent's king. To capture the opponent's piece, you must move one of your own pieces onto a square where an opponent's piece is residing. The board has 64 squares and each player has 16 pieces: 8 pawns, 2 knights, 2 bishops, 2 rooks, 1 queen and 1 king. Each of these pieces has a specific way in which they are allowed to move within a game.
The Pawn
The pawns must move only ahead. If it is the first time that particular pawn is being moved in the game it is allowed to move two squares ahead. A pawn can only capture another piece by moving one square diagonally. If a pawn makes it all the way to the back row of the opponent's side of the board it can be promoted to either a bishop, knight, rook, or queen.
The Knight
The knights move and capture in an "L" formation by either moving two squares horizontally and one square back or forward, or by moving two squares vertically then one square right or left. The knight is the only piece that is allowed to "jump" other pieces.
The Bishop
The bishops move and capture diagonally. They are allowed to move any number of squares in one move, but are not allowed to "jump" other pieces.
The Rook
The rooks, on the other hand, can move and capture vertically and horizontally. They are also allowed to move any number of squares at one time, and can not "jump" other pieces.
The Queen
The queens combine all the moves of the aforementioned pieces into one powerful piece. They are allowed to move any number of squares in a vertical, horizontal, or diagonal motion. The only move a queen is not allowed to make is "jumping" other pieces. The queen is a very versatile piece and that is why it is important to try to get one's pawns to the opponent's back line for promotion.
The King
Capturing the opponent's king is the ultimate object of chess. The kings are also the most limited in how they can move. Kings are allowed to move only one square in any direction, and that square has to be safe from an opponent's attack. If the king is in a position where it is vulnerable to attack by the opponent's piece then it is "in check" and must move to a safe position on the board. If there is no safe place for the king to move, and the king can't capture the threatening piece, it is in "checkmate" and the opponent wins the game.
Other than the above moves, there are a few special moves allowed in the game of chess. Two of these moves are castling and en passant.
Castling
Castling is a defensive strategy. In order to castle, the king and the rook need to be in their original positions on the board and the spaces between the rook and king must be empty. To castle, move the king to the second to last space on the board, then move the rook to the space on other side of the king. In order for castling to be effective, a player does not move the king, only the rook in defensive moves. This move allows one to concentrate more on attacking the king of the opponent rather than defending their own king.
En Passant
En Passant is a move for the pawn, and in french means "while passing" because the pawn is essentially capturing a square that was passed over by another pawn. En Passant can be used when an opponent moves their pawn two spaces on it's first move. The player will then move their pawn diagonally and "capture" the square the opponent's pawn passed over. This move is only allowed to be done in the turn after the opponent moved their pawn two spaces. The opponent's pawn will be taken off of the board.