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

DOC# file extension

Microsoft Word Document

Text Files

EPUB file extension

Open eBook File

eBook Files

7Z file extension

7-Zip Compressed File

Compressed Files

SQL file extension

Structured Query Language Data File

Database Files

MDB file extension

Microsoft Access Database

Database Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

AIF file extension

Audio Interchange File Format

Audio Files

PPS file extension

PowerPoint Slide Show

Data Files

ICNS file extension

Mac OS X Icon Resource File

System Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

VB file extension

VBScript File

Executable Files

MAX file extension

3ds Max Scene File

3D Image Files

ASX file extension

Microsoft ASF Redirector File

Video Files

DRV file extension

Device Driver

System Files

SDF file extension

Standard Data File

Data Files