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

LOG file extension

Log File

Text Files

HTM file extension

Hypertext Markup Language File

Web Files

ZIPX file extension

Extended Zip File

Compressed Files

CS file extension

Visual C# Source Code File

Developer Files

MPA file extension

MPEG-2 Audio File

Audio Files

7Z file extension

7-Zip Compressed File

Compressed Files

DOC file extension

Microsoft Word Document

Text Files

YUV file extension

YUV Encoded Image File

Raster Image Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

MOBI file extension

Mobipocket eBook

eBook Files

APP file extension

Mac OS X Application

Executable Files

AVI file extension

Audio Video Interleave File

Video Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

LUA file extension

Lua Source File

Developer Files

KML file extension

Keyhole Markup Language File

GIS Files