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

AIF file extension

Audio Interchange File Format

Audio Files

CGI file extension

Common Gateway Interface Script

Executable Files

DMP file extension

Windows Memory Dump

System Files

EPUB file extension

Open eBook File

eBook Files

FNT file extension

Windows Font File

Font Files

H file extension

C/C++/Objective-C Header File

Developer Files

ODT file extension

OpenDocument Text Document

Text Files

PHP file extension

PHP Source Code File

Web Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PS file extension

PostScript File

Vector Image Files

SQL file extension

Structured Query Language Data File

Database Files

TARGZ file extension

Compressed Tarball File

Compressed Files

THM file extension

Thumbnail Image File

Raster Image Files

TMP file extension

Temporary File

Backup Files

3DM file extension

Rhino 3D Model

3D Image Files