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

CSV file extension

Comma Separated Values File

Data Files

DDS file extension

DirectDraw Surface

Raster Image Files

DMP file extension

Windows Memory Dump

System Files

FLV file extension

Flash Video File

Video Files

GBR file extension

Gerber File

Data Files

GED file extension

GEDCOM Genealogy Data File

Data Files

M3U file extension

Media Playlist File

Audio Files

MP3 file extension

MP3 Audio File

Audio Files

MSG file extension

Outlook Mail Message

Text Files

NES file extension

Nintendo (NES) ROM File

Game Files

SRT file extension

SubRip Subtitle File

Video Files

TXT file extension

Plain Text File

Text Files

WSF file extension

Windows Script File

Executable Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files