CAT, Windows Catalog File (.cat)
The CAT System file format
CAT files are used on computers that run on the Windows operating system. It belongs to the category of system files and serves the purpose of marking a group of files as being from a trusted and verifiable source. Most commonly, CAT files are used to verify files that are downloaded for software updates.
Technical details of CAT files
CAT files group files together in a catalog. The files contain the catalog version, a digital signature, a date and the cryptographic hashes of all included files. By grouping files under the CAT file format, the download of software updates gets facilitated. The CAT file prevents the popup of several trust dialog windows for each file combined under the CAT file. Instead, users can choose to always trust files from a specific source.