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

ASPX file extension

Active Server Page Extended File

Web Files

BAT file extension

DOS Batch File

Executable Files

CSV file extension

Comma Separated Values File

Data Files

DEM file extension

Video Game Demo File

Game Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

GZ file extension

Gnu Zipped Archive

Compressed Files

HTM file extension

Hypertext Markup Language File

Web Files

JPG file extension

JPEG Image

Raster Image Files

ODT file extension

OpenDocument Text Document

Text Files

RA file extension

Real Audio File

Audio Files

SYS file extension

Windows System File

System Files

UUE file extension

Uuencoded File

Encoded Files

VCXPROJ file extension

Visual C++ Project

Developer Files

WMA file extension

Windows Media Audio File

Audio Files

3DS file extension

3D Studio Scene

3D Image Files