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

TOAST file extension

Toast Disc Image

Disk Image Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

XCODEPROJ file extension

Xcode Project

Developer Files

SLN file extension

Visual Studio Solution File

Developer Files

UUE file extension

Uuencoded File

Encoded Files

TEX file extension

LaTeX Source Document

Text Files

MP4 file extension

MPEG-4 Video File

Video Files

M3U file extension

Media Playlist File

Audio Files

MDF file extension

Media Disc Image File

Disk Image Files

JAR file extension

Java Archive File

Executable Files

ODT file extension

OpenDocument Text Document

Text Files

AVI file extension

Audio Video Interleave File

Video Files

AZW file extension

Amazon Kindle eBook File

eBook Files

7Z file extension

7-Zip Compressed File

Compressed Files

WSF file extension

Windows Script File

Executable Files