CAB (abbreviation for cabinet)
The file format CAB (abbreviation for cabinet) is a format for compressed archiving of files. The archive files usually have the file name extension .cab.
The CAB format allows to store multiple files in one archive file, including path information, and to extract the files together or individually. It is also possible to split the archive into several files (for example, to divide large files into pieces that each fit on a disk). Microsoft uses cab files for driver updates, for example.
For unpacking CAB files, the command line programs EXPAND and EXTRACT are available under Windows.
If the command line is too fiddly for you, you can use the open source software 7-Zip, for example. Other compression programs, also free of charge, can be found in a search engine.