Combo

A combo is a sequence of attacks that is guaranteed to occur if the first attack hits the enemy.

The exact definition of a combo may change from player to player, but the most accepted definition is any sequence of attacks that keeps the opponent in hitstun.

History
Combos exist in every Super Smash Bros. game. Combos are a crucial technique for low-high level play.Combos played a big role in choosing the tier list for the different games, usually the ones higher up are better to make combos than the ones in the bottom.

In Super Smash Flash
"Real" combos haven't been possible in the Super Smash Flash series until version 5a of the demo, where the knockback physics allow them, almost all characters can combo using different attacks, but some are still better than others