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

AVI file extension

Audio Video Interleave File

Video Files

CPL file extension

Windows Control Panel Item

System Files

CPP file extension

C++ Source Code File

Developer Files

CSV file extension

Comma Separated Values File

Data Files

DRV file extension

Device Driver

System Files

HTM file extension

Hypertext Markup Language File

Web Files

INDD file extension

Adobe InDesign Document

Layout Files

NES file extension

Nintendo (NES) ROM File

Game Files

PAGES file extension

Pages Document

Text Files

PHP file extension

PHP Source Code File

Web Files

RA file extension

Real Audio File

Audio Files

RTF file extension

Rich Text Format File

Text Files

TMP file extension

Temporary File

Backup Files

YUV file extension

YUV Encoded Image File

Raster Image Files

3G2 file extension

3GPP2 Multimedia File

Video Files