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

DDS file extension

DirectDraw Surface

Raster Image Files

DMP file extension

Windows Memory Dump

System Files

DNG file extension

Digital Negative Image File

Camera Raw Files

GED file extension

GEDCOM Genealogy Data File

Data Files

KEY file extension

Keynote Presentation

Data Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

MAX file extension

3ds Max Scene File

3D Image Files

PHP file extension

PHP Source Code File

Web Files

RA file extension

Real Audio File

Audio Files

RPM file extension

Red Hat Package Manager File

Compressed Files

RSS file extension

Rich Site Summary

Web Files

VB file extension

VBScript File

Executable Files