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

ASP file extension

Active Server Page

Web Files

CAB file extension

Windows Cabinet File

System Files

CBR file extension

Comic Book RAR Archive

Compressed Files

DBF file extension

Database File

Database Files

FLV file extension

Flash Video File

Video Files

GPX file extension

GPS Exchange File

GIS Files

GZ file extension

Gnu Zipped Archive

Compressed Files

H file extension

C/C++/Objective-C Header File

Developer Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

LNK file extension

Windows File Shortcut

System Files

M4V file extension

iTunes Video File

Video Files

MAX file extension

3ds Max Scene File

3D Image Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

SDF file extension

Standard Data File

Data Files

TIFF file extension

Tagged Image File Format

Raster Image Files