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

ASF file extension

Advanced Systems Format File

Video Files

ASP file extension

Active Server Page

Web Files

DEM file extension

Video Game Demo File

Game Files

EPUB file extension

Open eBook File

eBook Files

FLA file extension

Adobe Flash Animation

Developer Files

H file extension

C/C++/Objective-C Header File

Developer Files

INDD file extension

Adobe InDesign Document

Layout Files

JAVA file extension

Java Source Code File

Developer Files

LUA file extension

Lua Source File

Developer Files

MP3 file extension

MP3 Audio File

Audio Files

NES file extension

Nintendo (NES) ROM File

Game Files

THM file extension

Thumbnail Image File

Raster Image Files

TTF file extension

TrueType Font

Font Files

VCD file extension

Virtual CD

Disk Image Files

XML file extension

XML File

Data Files