Definition:Chess/Piece

Definition

There are a number of different kinds of chess piece.

They are distinguished by their modes of movement, as follows:

King

The king can be moved one square in any direction, including diagonally.

It cannot be moved into a position where it is in check.

Queen

The queen can be moved any number of squares in any of $8$ directions: forwards, backwards, left, right, and the $4$ diagonals.

It cannot be moved past a square occupied by another piece.

Bishop

The bishop can be moved any number of squares in any of the $4$ diagonal directions.

It cannot be moved past a square occupied by another piece.

Knight

The knight can be moved two squares in any orthogonal direction (up, down, left or right), and then one square at right angles to that direction.

It passes over intervening pieces and does not stop until reaching the end of its move.

It cannot be moved onto a square occupied by another piece of the same colour.

Rook

The rook can be moved any number of squares in any of the $4$ orthogonal directions: up, down, left or right.

It cannot be moved past a square occupied by another piece.

Pawn

A pawn may move in the following modes.

$(1): \quad$ It may move one square towards the opposing player, if and only if that square is empty.

$(2): \quad$ If it has not yet been moved, and if and only if both of the squares are empty, it may move $2$ squares forward instead of $1$.

Some authorities do not classify the pawn as a piece.