Insufficient material
Some positions cannot be checkmated by force, or at all, with the pieces left. The game is a draw when neither side has enough material to mate.
King against king is a draw. King and bishop against king is a draw. King and knight against king is a draw. There is no mate with those pieces.
King and two knights against a lone king cannot force mate, though a mate position exists if the defender makes a mistake. The forced result is a draw if the defender avoids the corner.
King and pawn, king and rook, king and queen, king and bishop and knight, and king and two bishops can all force mate against a lone king, if the technique is known. Those are the endgame pages.
On the board
8
7
6
5
4
3
2
a1
b
c
d
e
f
g
h
King against king. Move either king. No checkmate is possible.
Common mistakes
- Resigning king and bishop against king. It is a draw.
- Assuming two knights force mate against a lone king. They do not.
- Agreeing a draw with a queen still on the board against a lone king. That is not insufficient material.