Lesson 06

Check

• The king is the most important piece belonging to each player, though not the most powerful.
•  If a player moves a piece such that it threatens to capture his opponent's king, that king is said to be in check.
• If a player's king is in check, he must immediately remove the check by 

1. Moving the king.
2. Blocking the check with another piece. 
3. Capturing the checking piece.

• As mentioned above, players may not place their own king in check; however, they may check their opponent's king. 
• Two kings may never occupy adjacent squares, since they would have put themselves in check by moving there.

• above position white king check by black rook. White can capture the rook (Bxc1) or blocking the 1st rank (Bg1) or moving the king (Kh2).

Checkmate

• If the king is placed in check and cannot escape, it is said to have been checkmated (or "mated" for short).
• The first player to checkmate the opponent's king wins the game.
• Note that the king is never actually captured, since it is obliged to move out of check whenever possible (and the game ends when it is impossible).

• Black king in check (by white queen & two rook) and he cannot escape. Now black is checkmated and he lost the game.