An overloaded piece is one that must defend two or more important targets at once. When the attacker creates an additional threat, the overloaded piece must choose which duty to fulfill, inevitably abandoning one of its responsibilities. This allows the attacker to exploit the undefended target.
A common overloading scenario involves a queen that must simultaneously defend a back-rank mate threat and protect a hanging piece. If the opponent forces the queen to address one threat, the other becomes exploitable. Similarly, a knight defending both a bishop and a critical square can be overloaded by attacking one of the pieces it protects.
Recognizing overloaded pieces is a hallmark of strong tactical play. When analyzing a position, identify pieces that serve multiple defensive functions and look for ways to add pressure. Even if no immediate tactic exists, maneuvering to overload a key defender is a powerful strategic approach.