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

BAT file extension

DOS Batch File

Executable Files

CFM file extension

ColdFusion Markup File

Web Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DRV file extension

Device Driver

System Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

DXF file extension

Drawing Exchange Format File

CAD Files

INI file extension

Windows Initialization File

Settings Files

JAVA file extension

Java Source Code File

Developer Files

M4A file extension

MPEG-4 Audio File

Audio Files

MOBI file extension

Mobipocket eBook

eBook Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

RA file extension

Real Audio File

Audio Files

SDF file extension

Standard Data File

Data Files

UUE file extension

Uuencoded File

Encoded Files

VOB file extension

DVD Video Object File

Video Files