Generic database file that stores information in a structured format; might be created by a number of different database programs; may also be imported by multiple database programs.

An X-Ray Engine database stores objects used by games developed with the X-Ray Engine. It is similar to a .GCF file, which is used by Valve games.

The X-ray Engine is a DirectX Shader Model 3 graphics engine that supports up to a million polygons at once. It is used by the S.T.A.L.K.E.R. series of games developed by GSC Game World.

Files named Thumbs.db are image cache files created by Windows. They store small versions of the images contained in the folder.

Thumbs.db files help speed up image browsing within a folder, since the image thumbnails don't have to be recreated each time the folder is opened. These files are hidden by default, but may be seen if the "Show invisible files" option is checked in the "View options" window.