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

CAB file extension

Windows Cabinet File

System Files

DEB file extension

Debian Software Package

Compressed Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DRV file extension

Device Driver

System Files

EPUB file extension

Open eBook File

eBook Files

IFF file extension

Interchange File Format

Audio Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

LOG file extension

Log File

Text Files

MPA file extension

MPEG-2 Audio File

Audio Files

MSG file extension

Outlook Mail Message

Text Files

RA file extension

Real Audio File

Audio Files

SAV file extension

Saved Game

Game Files

SRT file extension

SubRip Subtitle File

Video Files

THM file extension

Thumbnail Image File

Raster Image Files

WPS file extension

Microsoft Works Word Processor Document

Text Files