A stomp is the second part of a jump that occurs while coming down. The player does not have to jump; the character can also fall off a ledge or cliff, or, as seen in New Super Mario Bros. Wii, use a Cannon Pipe. If the character stomps on top of an enemy or switch, the player can defeat the enemy or activate the switch. Stomping on enemies is Mario's primary attack, but it won't work on spiked or fire enemies and can return damage. It doesn't work on ceiling or transparent enemies. Boos are an exception; Mario or Luigi cannot stomp on them in the some of the Mario side-scrolling platformer games, but they can in the other games. Characters can stomp on opponents in Super Smash Bros. Brawl.
Anyone who can jump has the ability to stomp. In the Mario role-playing games, Mario uses it with a Action Command for extra damage. In the Mario Party series, the player can jump on a rival to stun them briefly, though it is still not as strong as a Ground Pound.