This article is about the in-game object. For the file format, see Level file.
Levels are the simulated environments in which all Marathon games take place. A single game session only simulates events in one level at a time, regardless of whether it's running on a single computer or a network. However, the game can switch between levels during a game session if a player activates a teleport-capable terminal or polygon leading to another level. (In Pathways Into Darkness, the player must walk into a teleporter or climb a ladder to change levels.)
Levels are sometimes referred to as "maps", but the word "map" can also refer to a type of data file which can contain multiple levels.