The Warp Pipe is usually a green pipe that allows a character to warp from the pipe to another pipe, though the colour has been known to vary. They first appeared in Super Mario Bros., largely as a means by which Mario can reach secret areas of the game. Their use is similar in all other 2D Mario platformers, such as Super Mario World, Super Mario Land and New Super Mario Bros., and in many of the RPGs that include them (Mario & Luigi: Partners in Time, Paper Mario). In Super Mario 64 and Super Mario 64 DS, the playable characters enter Princess Peach's Castle using Warp Pipes, yet their function later on in the game, in Tiny-Huge Island, is different. Here, they serve as a means of growing larger or smaller, switching between the two ways the level can be played. In Super Mario Sunshine, there are a few pipes that lead to secret areas, one of them, however leading to Sirena Beach, in which the help of Yoshi is required for access, and one leading to Pianta Village. In Super Smash Bros. Brawl, Mario and Luigi enter battles through green warp pipes.
Warp Pipes have been known to shoot out Bullet Bills. Often, Piranha Plants use warp pipes for hiding places, and will jump in and out of them attempting to damage a passer-by. They will often stay inside the warp pipe, however, when Mario or another person is standing on top of the pipe.
In Super Mario World 2: Yoshi's Island, Shy Guys, among other enemies, would often spawn in warp pipes, providing Yoshi with a source of free eggs. If a Yoshi were to go down into the warp pipe, they would find a dark cave where Shy Guys would come out of the floor of the cavern.