Sometimes a chess piece is overloaded by having more than one defensive job to do. The overworked piece can be exploited by capturing one of the pieces it is defending or occupying a square it is defending forcing it to leave its other defensive job.
In the diagram below, the Black Rook is overloaded. It is defending the Bishop and the Knight. How can White exploit this unfortunate position?
White wins a piece by playing: 1.Bxd3 and after 1...Rxd3 is a piece ahead after 2.Rxb7
In the diagram below can you see which of Black's pieces is overloaded and how White took advantage of it?