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

C file extension

C/C++ Source Code File

Developer Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

GED file extension

GEDCOM Genealogy Data File

Data Files

GPX file extension

GPS Exchange File

GIS Files

ISO file extension

Disc Image File

Disk Image Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

LOG file extension

Log File

Text Files

MP4 file extension

MPEG-4 Video File

Video Files

PS file extension

PostScript File

Vector Image Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

PY file extension

Python Script

Developer Files

WMA file extension

Windows Media Audio File

Audio Files

WPD file extension

WordPerfect Document

Text Files

WSF file extension

Windows Script File

Executable Files

3DS file extension

3D Studio Scene

3D Image Files