File extensions – definition and basic information


File extensions are the integral parts of the files that are on each computer. Often, when working on a computer, we encounter a wide range of files, such as docx, ppt, part, mp3 or rmvb. We realize that they are there – but we often do not know what they are for on our computer.

File extension, also known as the filename extension is a suffix added to the name of a computer file, usually consisting of a number of characters placed after the last dot in the filename, which gives us information about its coding. In other words a file extension is a file format. It allows the operating system (e.g. Windows) to recognize what program it should try to open the file.

In the table below you will find a random selection of popular file extensions.


File extension The full name of the file Category

SQL file extension

Structured Query Language Data File

Database Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

CAB file extension

Windows Cabinet File

System Files

WAV file extension

WAVE Audio File

Audio Files

MPA file extension

MPEG-2 Audio File

Audio Files

MPG file extension

MPEG Video File

Video Files

TORRENT file extension

BitTorrent File

Misc Files

RA file extension

Real Audio File

Audio Files

VOB file extension

DVD Video Object File

Video Files

BIN file extension

Binary Disc Image

Disk Image Files

LNK file extension

Windows File Shortcut

System Files

7Z file extension

7-Zip Compressed File

Compressed Files

TTF file extension

TrueType Font

Font Files

INDD file extension

Adobe InDesign Document

Layout Files

PRF file extension

Outlook Profile File

Settings Files