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

ASX file extension

Microsoft ASF Redirector File

Video Files

CAB file extension

Windows Cabinet File

System Files

CPL file extension

Windows Control Panel Item

System Files

CSV file extension

Comma Separated Values File

Data Files

DDS file extension

DirectDraw Surface

Raster Image Files

EPUB file extension

Open eBook File

eBook Files

GPX file extension

GPS Exchange File

GIS Files

JAR file extension

Java Archive File

Executable Files

M3U file extension

Media Playlist File

Audio Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

PDF file extension

Portable Document Format File

Layout Files

PIF file extension

Program Information File

Executable Files

SAV file extension

Saved Game

Game Files

3G2 file extension

3GPP2 Multimedia File

Video Files