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

ASP file extension

Active Server Page

Web Files

AVI file extension

Audio Video Interleave File

Video Files

BAT file extension

DOS Batch File

Executable Files

CGI file extension

Common Gateway Interface Script

Executable Files

GED file extension

GEDCOM Genealogy Data File

Data Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

HTML file extension

Hypertext Markup Language File

Web Files

LNK file extension

Windows File Shortcut

System Files

LUA file extension

Lua Source File

Developer Files

NES file extension

Nintendo (NES) ROM File

Game Files

PHP file extension

PHP Source Code File

Web Files

PPS file extension

PowerPoint Slide Show

Data Files

ROM file extension

N64 Game ROM File

Game Files

THM file extension

Thumbnail Image File

Raster Image Files

YUV file extension

YUV Encoded Image File

Raster Image Files