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

C file extension

C/C++ Source Code File

Developer Files

AVI file extension

Audio Video Interleave File

Video Files

RM file extension

Real Media File

Video Files

SAV file extension

Saved Game

Game Files

FON file extension

Generic Font File

Font Files

CUR file extension

Windows Cursor

System Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

ASPX file extension

Active Server Page Extended File

Web Files

HTML file extension

Hypertext Markup Language File

Web Files

DRV file extension

Device Driver

System Files

VCF file extension

vCard File

Data Files

M file extension

Objective-C Implementation File

Developer Files

BAK file extension

Backup File

Backup Files

LOG file extension

Log File

Text Files