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

BIN file extension

Binary Disc Image

Disk Image Files

CAB file extension

Windows Cabinet File

System Files

COM file extension

DOS Command File

Executable Files

DEB file extension

Debian Software Package

Compressed Files

DRV file extension

Device Driver

System Files

FON file extension

Generic Font File

Font Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

JPG file extension

JPEG Image

Raster Image Files

LOG file extension

Log File

Text Files

MOV file extension

Apple QuickTime Movie

Video Files

MSG file extension

Outlook Mail Message

Text Files

RM file extension

Real Media File

Video Files

RPM file extension

Red Hat Package Manager File

Compressed Files

SAV file extension

Saved Game

Game Files