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

CAB file extension

Windows Cabinet File

System Files

CLASS file extension

Java Class File

Developer Files

DBF file extension

Database File

Database Files

EXE file extension

Windows Executable File

Executable Files

FLV file extension

Flash Video File

Video Files

IBOOKS file extension

Multi-Touch iBook

Data Files

IFF file extension

Interchange File Format

Audio Files

JSP file extension

Java Server Page

Web Files

ODT file extension

OpenDocument Text Document

Text Files

PRF file extension

Outlook Profile File

Settings Files

SDF file extension

Standard Data File

Data Files

VCXPROJ file extension

Visual C++ Project

Developer Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

XCODEPROJ file extension

Xcode Project

Developer Files