The Warp Zone is a special area in Super Mario Bros and Super Mario Bros 3. In both cases, accessing the Warp Zone allows the player to skip ahead in the game to worlds that would otherwise be only available by following the linear progression of the game's levels. In Super Mario Bros this is usually done by either running or climbing to a secret area in the level. Super Mario Bros 3 featured the Warp Whistle, which whisked the player away to a Warp Zone. In the Warp Zone, the player is allowed to choose from either one or three pipes that are marked with the world to which they lead. Super Mario Bros 2 also featured warping, which could only be done by entering sub-space near certain vases in the game.
The Star Road
In Super Mario World, the Star Road essentially took the place of the Warp Zone. The Star Road could be accessed after the player found hidden exits in some of the regular levels. Star World was unique from Warp Zones in two ways: one was that it allowed for backward as well as forward travel through the game's worlds; second was that the Star Road contained its own levels, and the player had to find the hidden exit in each of those levels in order to access the higher levels on the road and the stars that would transport them to the highest levels of the game. In addition, the Star Road featured special Yoshis, and allowed access to the Special World, a collection of eight levels which are some of the most unique and challenging levels in the game.
By Super Mario 64, Warp Zones had outgrown their usefulness. The game featured a non-linear structure that opened new worlds based on how many stars the player had collected by completing levels. This level structure continued in Super Mario Sunshine and Super Mario Galaxy, negating the need for the player to perform special tasks to access the more advanced levels of the game, and rendering the Warp Zone a thing of the past.
Warp Zones in other games
Star Fox for the SNES featured a warp zone in the form of a black hole. The black hole could be opened in the Asteroid Belt by shooting the center of three rows of asteroids, then the face asteroid that appeared. Entering the black hole gave the player the opportunity to warp directly to Sector Y, Sector Z, or Venom (level 1.)
Super Meat Boy
In Super Meat Boy, the warp zone is less of a mode of rapid advancement, and more of a bonus area. Here the warp zone places Meat Boy in a level that looks like an 8-bit throwback, with flat, blocky graphics and chiptune sound. These special areas contain three levels with various bonuses for completion.