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

BMP file extension

Bitmap Image File

Raster Image Files

CPP file extension

C++ Source Code File

Developer Files

CUE file extension

Cue Sheet File

Disk Image Files

FLA file extension

Adobe Flash Animation

Developer Files

ICNS file extension

Mac OS X Icon Resource File

System Files

M file extension

Objective-C Implementation File

Developer Files

PART file extension

Partially Downloaded File

Misc Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PNG file extension

Portable Network Graphic

Raster Image Files

SH file extension

Bash Shell Script

Developer Files

SLN file extension

Visual Studio Solution File

Developer Files

VCD file extension

Virtual CD

Disk Image Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files