The goal of chess is to “checkmate” your opponent’s King.
Checkmate occurs when the “checked” king is unable to escape “check” from the opposing army.
When the King is in check, he MUST get out of check!.
The King can NEVER move to a square where he is attacked.
Checkmate is check PLUS the King is trapped: it can’t move, block, or capture the attacking piece.
If you are in check, your only options are ABC (Avoid [move], Block, or Capture)