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

M file extension

Objective-C Implementation File

Developer Files

EXE file extension

Windows Executable File

Executable Files

THM file extension

Thumbnail Image File

Raster Image Files

DOC file extension

Microsoft Word Document

Text Files

PAGES file extension

Pages Document

Text Files

CFM file extension

ColdFusion Markup File

Web Files

APP file extension

Mac OS X Application

Executable Files

BAT file extension

DOS Batch File

Executable Files

WMA file extension

Windows Media Audio File

Audio Files

MOV file extension

Apple QuickTime Movie

Video Files

JS file extension

JavaScript File

Web Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

XCODEPROJ file extension

Xcode Project

Developer Files

TIFF file extension

Tagged Image File Format

Raster Image Files

7Z file extension

7-Zip Compressed File

Compressed Files