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

ACCDB file extension

Access 2007 Database File

Database Files

AZW file extension

Amazon Kindle eBook File

eBook Files

BIN file extension

Binary Disc Image

Disk Image Files

CS file extension

Visual C# Source Code File

Developer Files

CSS file extension

Cascading Style Sheet

Web Files

DEB file extension

Debian Software Package

Compressed Files

DLL file extension

Dynamic Link Library

System Files

FON file extension

Generic Font File

Font Files

JPG file extension

JPEG Image

Raster Image Files

KEY file extension

Keynote Presentation

Data Files

RTF file extension

Rich Text Format File

Text Files

SQL file extension

Structured Query Language Data File

Database Files

TORRENT file extension

BitTorrent File

Misc Files

WPD file extension

WordPerfect Document

Text Files

WPS file extension

Microsoft Works Word Processor Document

Text Files