A natural combo is a move composed of multiple parts; pressing the relevant button at the correct time will launch the next segment of the move, while not pressing the button will end the sequence. Despite the similar terminology, natural combos are not always combos; the sequence of attacks is not guaranteed to hit the opponent if the first hit connects due to techniques like SDI.
The term is sometimes used interchangeably with neutral attack, its most common type; most characters will perform multiple attacks (such as Mario's jab, cross, kick), with some following into a rapid attack. Some characters, such as Snake, Bayonetta and Link, have natural combos using their tilts, aerials, or smashes, and some special moves, like Dancing Blade and Cross Slash, are natural combos as well.
List of natural combos