Another solution is offered by applications like Trid that scan the file and display those information on the local computer. This method has a few advantages over the Internet search. The first and most obvious one is that no Internet is required to identify the file and the second that there will be no danger of landing on a website that might lure the user into downloading malicious software.

Trid (via Shellcity) is actually a very sophisticated software that comes as a command line interface version, a Tridnet version that comes with a GUI, an online version that can be used on the Trid homepage and a scanner that can add new file extensions to the database.

Trid uses a database of definitions to identify files:

TrID uses a database of definitions which describe recurring patterns for supported file types. As this is subject to very frequent update, it’s made available as a separate package. Just download both TrID and this archive and unpack in the same folder.

New definitions can be added by scanning files on the system or by downloading the newest definition file from the Trid homepage.