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

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

CSS file extension

Cascading Style Sheet

Web Files

PKG file extension

Mac OS X Installer Package

Compressed Files

7Z file extension

7-Zip Compressed File

Compressed Files

BIN file extension

Binary Disc Image

Disk Image Files

DTD file extension

Document Type Definition File

Developer Files

M3U file extension

Media Playlist File

Audio Files

BMP file extension

Bitmap Image File

Raster Image Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

VCF file extension

vCard File

Data Files

UUE file extension

Uuencoded File

Encoded Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

DOC file extension

Microsoft Word Document

Text Files

PL file extension

Perl Script

Developer Files

JAR file extension

Java Archive File

Executable Files