Interference

Interference breaks the connection between two enemy pieces that depend on a line. The attacker places a piece between them on a vertical file, a horizontal rank, or a diagonal, so that a rook, bishop, or queen can no longer protect a piece or square on the other side.

The interfering piece is often offered as a sacrifice, meaning it may be captured in exchange for a greater gain. The key is that the capture may also pull a defender away, close another line, or allow an attack on the king. A sacrifice is not required by the definition, however; it is enough for the interposition to break a decisive connection.

To find the idea, trace the opponent's defensive lines and look for an intermediate square you can occupy with a threat. Interference can produce an effect similar to removal of the defender without a capture: the defender remains on the board, but its action no longer reaches the target. The term interception is often used for the same family of moves.