Checkerboard game for two players, each of whom moves 16 pieces
according to fixed rules across the board and tries to capture
or immobilize (checkmate) the opponent's king. The game may have
originated in Asia about the 6th century, though it continued to
evolve as it spread into Europe in Byzantine times; its now-
standard rules first became generally accepted in Europe in the
16th century. The players, designated white or black, start with
their pieces arranged on opposite ends of the board. Kings move
one square in any directionbut not into attack (check). Bishops
move diagonally, and rooks horizontally or vertically, any
number of unobstructed squares. Queens move like either bishops
or rooks. Knights move to the nearest nonadjacent square of the
opposite colour (an L shape) and ignore intervening chessmen.
Pieces capture by moving to an enemy-occupied square. Pawns move
forward one square (except one or two on their first move) and
are promoted to any non-king piece if they eventually reach the
last row.