.CAT File Extension

File used by the Windows operating system; specifies that a group of files are from a verifiable source; used for security purposes and contains a digital signature, the catalog version, and an effective date; often used for verifying new software update files.

Windows catalog files help to suppress multiple trust dialog popups for new software component downloads. Since CAT files can identify a trusted source, the user can choose to "Always trust content" from the software distributor. Then, future downloads from the software distributor that use a CAT file are trusted and do not require a trust popup window.

Contains a catalog of data from various media types including hard drives, network drives, floppy disks, optical discs (DVDs, CDs, etc.), ZIP and JAZ disks, etc.; used for keeping track of information stored within a collection of media