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

ASX file extension

Microsoft ASF Redirector File

Video Files

CGI file extension

Common Gateway Interface Script

Executable Files

CSR file extension

Certificate Signing Request File

Web Files

DOC file extension

Microsoft Word Document

Text Files

EXE file extension

Windows Executable File

Executable Files

FNT file extension

Windows Font File

Font Files

GAM file extension

Saved Game File

Game Files

JAR file extension

Java Archive File

Executable Files

KML file extension

Keyhole Markup Language File

GIS Files

LOG file extension

Log File

Text Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

RSS file extension

Rich Site Summary

Web Files

SDF file extension

Standard Data File

Data Files

SH file extension

Bash Shell Script

Developer Files