.001 File extension

A 001 file is the first file of a split archive created with various file splitting and joining utilities. It is used to split large archives into smaller, more manageable files. 001 files can be used for saving files onto multiple storage devices, such as USB drives or CDs, or for creating smaller email attachments.

An 001 file is one part of a larger archive, which means there is at least one more split archive associated with the file. Each part of a split archive is given an ascending number extension, which are .002, .003, etc. NOTE: Programs such as 7-Zip use compound extensions for split archives. For example, 7-Zip creates split archives with the .7Z.001, .7Z.002, etc. extensions.