Interference works by cutting the communication between enemy pieces that defend each other or control critical squares. By placing a piece (often through a sacrifice) on the square where their defensive lines intersect, the attacker forces the opponent to capture with one piece, thereby severing its connection to the other.
A classic interference pattern involves two rooks on the same rank defending each other. Placing a piece between them breaks the mutual defense, allowing the attacker to capture one rook without the other being able to recapture. This concept extends to any pair of pieces whose coordination depends on a clear line.
Interference is a more advanced tactical theme that often appears in complex combinations. It requires recognizing the geometric relationships between enemy pieces and finding the precise square where an interposing piece causes maximum disruption. In puzzles, interference motifs often lead to spectacular sacrifices.