A level editor (also known as a map, campaign or scenario editor) is a software tool used to design levels, maps, campaigns, etc and virtual worlds for a video game. In some cases the creator of a video game releases an official level editor for a game, but other times the community of fans step in to fill the void. An individual involved with the creation of game levels is a level designer or mapper.
Sometimes a level editor is integrated into the game; the features of the level editor will sometimes be disabled in the ship version of the software. Other times (and most often), the editor is a separate application, as are most fan-released level editors. A level editor is often used to create levels for a certain game engine. Developing a level editor takes a lot of time and it is more efficient to release multiple games using the same engine instead of developing a new engine and level editor for each game. Levels editors offer some limited scope of content creation, but in the case of games industry solutions the scope is very large allowing an entire game to be created without the need for much support from a programming team. To make larger changes to a game than simply adding new levels, a software development kit (SDK) is sometimes needed.
In the early years of video-gaming, some games came with a utility called a "construction set". This was similar in many ways to a level-editor. Some games used them to create extra levels, whereas others (like the Shoot'Em-Up Construction Kit) used them as a means to create a game rather than be a game in itself. Some examples of games with construction sets include: