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

CER file extension

Internet Security Certificate

Web Files

CRX file extension

Chrome Extension

Plugin Files

EPUB file extension

Open eBook File

eBook Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

GZ file extension

Gnu Zipped Archive

Compressed Files

LNK file extension

Windows File Shortcut

System Files

LOG file extension

Log File

Text Files

MID file extension

MIDI File

Audio Files

PPT file extension

PowerPoint Presentation

Data Files

VOB file extension

DVD Video Object File

Video Files

WPD file extension

WordPerfect Document

Text Files

WSF file extension

Windows Script File

Executable Files

YUV file extension

YUV Encoded Image File

Raster Image Files

3DM file extension

Rhino 3D Model

3D Image Files

3G2 file extension

3GPP2 Multimedia File

Video Files