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

AIF file extension

Audio Interchange File Format

Audio Files

BMP file extension

Bitmap Image File

Raster Image Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

HTML file extension

Hypertext Markup Language File

Web Files

INDD file extension

Adobe InDesign Document

Layout Files

JSP file extension

Java Server Page

Web Files

M4V file extension

iTunes Video File

Video Files

PART file extension

Partially Downloaded File

Misc Files

PDB file extension

Program Database

Database Files

PKG file extension

Mac OS X Installer Package

Compressed Files

RSS file extension

Rich Site Summary

Web Files

SLN file extension

Visual Studio Solution File

Developer Files

TMP file extension

Temporary File

Backup Files

VCD file extension

Virtual CD

Disk Image Files

ZIP file extension

Zipped File

Compressed Files