An 000 file is a data file created by Indexing Service, a software component of the Windows operating system that creates a searchable file system index from files on the hard drive. The data stored in a 000 file helps Windows perform quick searches.

000 files are saved with several other types of files that make up the search index. Other types may include .BK1, .BK2, .FID, .HSH, .PS1, and .PS2 files. The Indexing Service search index is typically created in the following directory: C:\System Volume Information\catalog.wci The index may also be generated for external volumes connected to a Windows computer, such as USB flash drives. If you have a slow CPU, you should consider disabling indexing or selectively disabling indexing on your computer. To do this, click Start or the search bar in Windows and type "indexing" in the search field. Then, click Indexing Options and remove locations in Windows that you no longer want to be indexed. This will increase the amount of time it takes Windows to search these locations but will also improve the performance of the CPU.

Disc image data file created by Virtual CD, a disc imaging program; created by versions 4 and later of the software; contains the data for the disc and is saved alongside a .VC4 file; may also be saved with a .VCX file, which is the CD Editor project that was used to create the 000 and VC4 files.

000 files can be burned to a disc using Virtual CD. However, you need to open the corresponding VC4 file (or VCX file if it exists), which then allows the Virtual CD software to access the disc image.

Index of cabinet (.CAB) files included in an installation package for a Windows CE device; referenced by the program's installer script and defines the files to be installed.

Cabinet index files also include the application name and publisher, the designated directory path for installation, WinCE software requirements, the cabinet architecture, and other information.