The middlegame in chess refers to the part of a game after the opening struggle, and before the beginning of the endgame. In this phase of the game, both players attempt to strengthen their positions while weakening their opponent's, with a combination of planned attacks aimed at the king and by wittling down the opponent's resources. It's usually a fight over a pawn or a square, perhaps an open file. The line between where the middlegame ends and the endgame begins is difficult to define, as both parts usually blend into each other.