Doom Builder is an advanced, revolutionary map editor for Doom and games based on the Doom engine, such as Heretic, Hexen and Strife. This editor is highly extendible for the different game engines of the Doom community. Doom Builder introduced the 3D editing mode in the Doom community and is still the leading editor for Doom levels today.
This is the Reference Manual for Doom Builder 2. You can use this manual to look up how the editor works and what the specific modes and actions do. This manual is not a beginners tutorial that teaches you how to make maps.