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

AVI file extension

Audio Video Interleave File

Video Files

CER file extension

Internet Security Certificate

Web Files

CFM file extension

ColdFusion Markup File

Web Files

CGI file extension

Common Gateway Interface Script

Executable Files

CPP file extension

C++ Source Code File

Developer Files

DDS file extension

DirectDraw Surface

Raster Image Files

DOC file extension

Microsoft Word Document

Text Files

DOC# file extension

Microsoft Word Document

Text Files

FON file extension

Generic Font File

Font Files

M file extension

Objective-C Implementation File

Developer Files

MSG file extension

Outlook Mail Message

Text Files

PL file extension

Perl Script

Developer Files

PY file extension

Python Script

Developer Files

TEX file extension

LaTeX Source Document

Text Files

TIFF file extension

Tagged Image File Format

Raster Image Files