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

ACCDB file extension

Access 2007 Database File

Database Files

AIF file extension

Audio Interchange File Format

Audio Files

CRX file extension

Chrome Extension

Plugin Files

INI file extension

Windows Initialization File

Settings Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

LNK file extension

Windows File Shortcut

System Files

MDF file extension

Media Disc Image File

Disk Image Files

MPA file extension

MPEG-2 Audio File

Audio Files

PY file extension

Python Script

Developer Files

RM file extension

Real Media File

Video Files

SDF file extension

Standard Data File

Data Files

SRT file extension

SubRip Subtitle File

Video Files

THM file extension

Thumbnail Image File

Raster Image Files

TORRENT file extension

BitTorrent File

Misc Files

WSF file extension

Windows Script File

Executable Files