World

A world is a group of levels in Mario games. In Super Mario Bros. and Super Mario Bros.: The Lost Levels, each world always has exactly four levels, and in Super Mario Bros. 2, each world has three (except the final world, which has only two). However, starting in Super Mario Bros. 3, most games have a varying number of levels. In some three-dimensional Mario games, worlds are no longer used; now each level stands alone (but each level is sometimes referred to as a world), and the missions are referred to as either stars or episodes. In earlier games, worlds were simply numbered "World 1," "World 2," etc. Super Mario Bros. 3 was the first Mario game to give the worlds distinct names, though some later games return to the standard numerical naming.

In general terms, a world refers to any large area of land and space marked off from other regions. As such, "world" may refer to a politically or geographically distinct region of land (such as Desert Land or Chocolate Island), a planet, or even an entire galaxy. Each world has several different terrains and locations.