A fork is one piece attacking two or more of the opponent's pieces at the same time. The opponent can usually save only one of them. Knights fork most often, because their jumps are hard to see coming, but every piece can fork, the king and the pawns too. Look for two enemy pieces that are unprotected, or the king and a loose piece, and ask which of your pieces could reach a square that attacks both.
Below are three puzzles on this theme from the Lichess puzzle database, from easier to harder. Each one is solved move by move, with what every move does and what the line wins.
Puzzle 1: rated 915
White has just played 32.Rf7, the arrow on the diagram. Black to move. Lichess rates this puzzle 915, from 22,625 attempts. Try it before you read on, or set it up on a board.
The solution
- 32...Ng3+: the knight goes to g3, with check.
- 33.Kg2: the king goes to g2.
- 33...Nxf1: the knight takes the rook on f1.
Ng3+ forks the king on h1 and the rook on f1. By the end of the line, Black has taken a rook, so Black is ahead by 5 points of material.
Puzzle 2: rated 1,181
Black has just played 28...Qxd5, the arrow on the diagram. White to move. Lichess rates this puzzle 1,181, from 18,150 attempts. Try it before you read on, or set it up on a board.
The solution
- 29.Nf6+: the knight goes to f6, with check.
- 29...Kf7: the king goes to f7.
- 30.Nfxd5: the knight takes the queen on d5.
Nf6+ forks the king on g8 and the queen on d5. By the end of the line, White has taken a queen, so White is ahead by 9 points of material.
Puzzle 3: rated 1,626
Black has just played 36...Qxg4, the arrow on the diagram. White to move. Lichess rates this puzzle 1,626, from 4,824 attempts. Try it before you read on, or set it up on a board.
The solution
- 37.Nf6+: the knight goes to f6, with check.
- 37...Kf8: the king goes to f8.
- 38.Nxd7+: the knight takes the queen on d7, with check.
- 38...Ke7: the king goes to e7.
- 39.Qxg4: the queen takes the queen on g4.
Nf6+ forks the king on g8 and the queen on d7. By the end of the line, White has taken two queens, so White is ahead by 18 points of material.
Keep practising
The lesson Forks teaches the idea step by step, with positions to solve. GreyChess's rated puzzles come from the same Lichess database, sorted by theme and rating, so you can practise this tactic at your own level.