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

AVI file extension

Audio Video Interleave File

Video Files

CAB file extension

Windows Cabinet File

System Files

CPP file extension

C++ Source Code File

Developer Files

CRX file extension

Chrome Extension

Plugin Files

DAT file extension

Data File

Data Files

DOC file extension

Microsoft Word Document

Text Files

IBOOKS file extension

Multi-Touch iBook

Data Files

IFF file extension

Interchange File Format

Audio Files

JAVA file extension

Java Source Code File

Developer Files

MAX file extension

3ds Max Scene File

3D Image Files

ODT file extension

OpenDocument Text Document

Text Files

PPS file extension

PowerPoint Slide Show

Data Files

RA file extension

Real Audio File

Audio Files

TGA file extension

Targa Graphic

Raster Image Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files