Supersets combine 2 or more exercises with no rest between them. The goal is to maximize the amount of work of a muscle or group of muscles.
Antagonist supersets
Working antagonist muscle groups (e.g.: biceps/triceps).
Pre-exhaustion supersets
Doing an isolation exercise before a compound exercise. The isolation exercise first exhausts the muscle group, and then the compound exercise uses the muscle group's supporting muscles to push it further than would otherwise be possible. For example, the triceps muscles normally help the pectorals perform their function. But in the "bench press" the weaker triceps often fails first, which limits the impact on the pectorals. By preceding the bench press with the pec fly, the pectorals can be pre-exhausted so that both muscles fail at the same time, and both benefit equally from the exercise.
Giant set
Three or more exercises (related to Circuit Training).
Supersets put a lot of stress on your body, do not do them every workout.