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

AI file extension

Adobe Illustrator File

Vector Image Files

CER file extension

Internet Security Certificate

Web Files

CSR file extension

Certificate Signing Request File

Web Files

CUE file extension

Cue Sheet File

Disk Image Files

FLV file extension

Flash Video File

Video Files

FNT file extension

Windows Font File

Font Files

GAM file extension

Saved Game File

Game Files

M file extension

Objective-C Implementation File

Developer Files

MID file extension

MIDI File

Audio Files

PY file extension

Python Script

Developer Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

3DM file extension

Rhino 3D Model

3D Image Files