IM stands for Individual Medley in the context of swimming. Individual Medley is a swimming event where the swimmer competes in all four competitive swimming strokes (butterfly, backstroke, breaststroke, and freestyle) in a specific order. The swimmer must swim equal distances of each stroke, usually in the order of butterfly, backstroke, breaststroke, and freestyle. This event showcases the swimmer's versatility and ability to perform different strokes effectively.