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

GBR file extension

Gerber File

Data Files

7Z file extension

7-Zip Compressed File

Compressed Files

TIF file extension

Tagged Image File

Raster Image Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

PPS file extension

PowerPoint Slide Show

Data Files

CER file extension

Internet Security Certificate

Web Files

MP3 file extension

MP3 Audio File

Audio Files

COM file extension

DOS Command File

Executable Files

ASPX file extension

Active Server Page Extended File

Web Files

ISO file extension

Disc Image File

Disk Image Files

AVI file extension

Audio Video Interleave File

Video Files

CAB file extension

Windows Cabinet File

System Files

INDD file extension

Adobe InDesign Document

Layout Files

DRV file extension

Device Driver

System Files

WMA file extension

Windows Media Audio File

Audio Files