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

DDS file extension

DirectDraw Surface

Raster Image Files

CER file extension

Internet Security Certificate

Web Files

TGA file extension

Targa Graphic

Raster Image Files

XML file extension

XML File

Data Files

7Z file extension

7-Zip Compressed File

Compressed Files

VCXPROJ file extension

Visual C++ Project

Developer Files

DOC file extension

Microsoft Word Document

Text Files

DRV file extension

Device Driver

System Files

GADGET file extension

Windows Gadget

Executable Files

CAB file extension

Windows Cabinet File

System Files

BAK file extension

Backup File

Backup Files

AIF file extension

Audio Interchange File Format

Audio Files

DOC# file extension

Microsoft Word Document

Text Files

PDF file extension

Portable Document Format File

Layout Files

WPS file extension

Microsoft Works Word Processor Document

Text Files