The following tutorial describes 6 most common file types that you will encounter while using Hammer Source and SourceSDK/Authoring tools.
It's important to know these file types are and their purpose.
6 Common File Types are:
.bsp - file extension for maps/levels
.vmt - Valve Material Type. Text file that contains information for Source Engine to simulate surface types.
.vtf - Valve Texture Format. Texture format used by Source Engine.
.nav - Navigation Mesh file for bots. Walkable space in the map for bots to navigate around.
.vpk - Valve Pack File. Uncompressed archive used to package maps content. Such as campaign files for L4D2.
.vmt - Valve Map File. Raw map file data. File type used in Hammer Source Editor. This contains all the entities, brushes and textures that you see in Hammer Editor.
