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

BIN file extension

Binary Disc Image

Disk Image Files

CFM file extension

ColdFusion Markup File

Web Files

DB file extension

Database File

Database Files

DRV file extension

Device Driver

System Files

DXF file extension

Drawing Exchange Format File

CAD Files

KEY file extension

Keynote Presentation

Data Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

OTF file extension

OpenType Font

Font Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

ROM file extension

N64 Game ROM File

Game Files

RSS file extension

Rich Site Summary

Web Files

TTF file extension

TrueType Font

Font Files

UUE file extension

Uuencoded File

Encoded Files

WPD file extension

WordPerfect Document

Text Files

XLR file extension

Works Spreadsheet

Spreadsheet Files