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

CPL file extension

Windows Control Panel Item

System Files

DOC file extension

Microsoft Word Document

Text Files

DRV file extension

Device Driver

System Files

GZ file extension

Gnu Zipped Archive

Compressed Files

ICNS file extension

Mac OS X Icon Resource File

System Files

SH file extension

Bash Shell Script

Developer Files

SLN file extension

Visual Studio Solution File

Developer Files

SRT file extension

SubRip Subtitle File

Video Files

TEX file extension

LaTeX Source Document

Text Files

TGA file extension

Targa Graphic

Raster Image Files

TIFF file extension

Tagged Image File Format

Raster Image Files

WMV file extension

Windows Media Video File

Video Files

WPD file extension

WordPerfect Document

Text Files

3G2 file extension

3GPP2 Multimedia File

Video Files