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

AIF file extension

Audio Interchange File Format

Audio Files

ASPX file extension

Active Server Page Extended File

Web Files

BIN file extension

Binary Disc Image

Disk Image Files

CRX file extension

Chrome Extension

Plugin Files

CUR file extension

Windows Cursor

System Files

DMP file extension

Windows Memory Dump

System Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

HTML file extension

Hypertext Markup Language File

Web Files

ISO file extension

Disc Image File

Disk Image Files

M file extension

Objective-C Implementation File

Developer Files

MDF file extension

Media Disc Image File

Disk Image Files

RA file extension

Real Audio File

Audio Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

YUV file extension

YUV Encoded Image File

Raster Image Files

3DS file extension

3D Studio Scene

3D Image Files