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

AZW file extension

Amazon Kindle eBook File

eBook Files

CRX file extension

Chrome Extension

Plugin Files

DLL file extension

Dynamic Link Library

System Files

DTD file extension

Document Type Definition File

Developer Files

FLV file extension

Flash Video File

Video Files

ISO file extension

Disc Image File

Disk Image Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

LNK file extension

Windows File Shortcut

System Files

M3U file extension

Media Playlist File

Audio Files

MDF file extension

Media Disc Image File

Disk Image Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

TEX file extension

LaTeX Source Document

Text Files

TIFF file extension

Tagged Image File Format

Raster Image Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

ZIPX file extension

Extended Zip File

Compressed Files