From the Super Mario Wiki
Ads keep the MarioWiki independent and free :)
This article is about the general overview of levels. For for a list of every level, see Category:Levels and its subcategories.
Clockwise from top left: level endings of Super Mario Bros., Super Mario Bros. 2, Super Mario World, and Super Mario Bros. 3

All platformers have multiple levels (also called courses or stages) which contain obstacles, enemies, items, and the like. Mario (or other characters) must pass through one level to get to the next and ultimately complete the game. In some cases, there are also levels that are hidden and need to be unlocked.

Levels appear in the Super Mario series. At the end of every level (except for fortress, tower, airship, and castle levels) in Super Mario Bros., Super Mario Bros.: The Lost Levels, New Super Mario Bros., New Super Mario Bros. Wii, New Super Mario Bros. 2, and New Super Mario Bros. U is a Goal Pole (or a Red Flagpole if it is a secret exit in the New Super Mario Bros. games) and Fortress. However, Super Mario 3D Land and Super Mario 3D World contain Goal Poles at the end of every level. Regular levels in Super Mario Bros. 2 end with a Mask Gate, opened after taking a crystal ball usually guarded by Birdo, while in the last level of each world a door appears after defeating the boss. Most levels of Super Mario Bros. 3 end with roulette-like goals, but Fortresses end with fighting Boom Boom and Airships pit Mario or Luigi against a Koopaling. Most levels of Super Mario World end with Giant Gates, but the castles end with fighting a Koopaling, while the fortresses culminate with fighting Reznor. Levels in Super Mario Land end with Mario entering a tower, while in Super Mario Land 2: 6 Golden Coins he has to hit a bell; in both of these games, the last level of each world ends automatically when the boss is defeated. Super Paper Mario has Star Blocks at the end of every sub-chapter after the chapter boss is defeated. In Super Mario 64, Super Mario Galaxy, and Super Mario Galaxy 2, levels end with the collection of a Power Star, while in Super Mario Sunshine, they end with the collection of a Shine Sprite. Each game has a unique ending for its levels, although the outcome is always progression to the next level.

To coincide with the games, each chapter in the Super Mario-Kun is referred to as a level.