As stated before, the purpose of the game is to checkmate the opponents king. This happens when the king is put into check and cannot get out of check. There are only three ways a king can get out of check: move out of the way, block the check with another piece, or capture the piece threatening the king. If a king cannot escape checkmate then the game is over. Customarily the king is not captured or removed from the board, the game is simply declared over.