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

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

CRX file extension

Chrome Extension

Plugin Files

BMP file extension

Bitmap Image File

Raster Image Files

ZIP file extension

Zipped File

Compressed Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

UUE file extension

Uuencoded File

Encoded Files

JPG file extension

JPEG Image

Raster Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

IFF file extension

Interchange File Format

Audio Files

LUA file extension

Lua Source File

Developer Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

AVI file extension

Audio Video Interleave File

Video Files

MOBI file extension

Mobipocket eBook

eBook Files

JS file extension

JavaScript File

Web Files

KEY file extension

Keynote Presentation

Data Files