Desperado tactics arise when a piece is under attack and cannot be saved. Instead of simply allowing the capture, the player uses the doomed piece to capture an enemy piece, give check, or create some other threat. Since the piece is lost regardless, any damage it inflicts is essentially free.
A common desperado scenario occurs during piece exchanges. If both players have hanging pieces, the first player to capture with their "desperado" piece gains material. For example, if White's bishop and Black's knight are both en prise, White might capture a pawn with the bishop before it gets taken, netting an extra pawn from the exchange.
Desperado thinking is important in complex tactical positions where multiple pieces are under attack. Before accepting a material loss, always check whether the threatened piece can inflict damage on its way out. This principle applies to all pieces but is especially relevant for pieces deep in enemy territory.