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

ASPX file extension

Active Server Page Extended File

Web Files

7Z file extension

7-Zip Compressed File

Compressed Files

PIF file extension

Program Information File

Executable Files

CS file extension

Visual C# Source Code File

Developer Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

PY file extension

Python Script

Developer Files

DOC file extension

Microsoft Word Document

Text Files

M3U file extension

Media Playlist File

Audio Files

LNK file extension

Windows File Shortcut

System Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

PS file extension

PostScript File

Vector Image Files

ASX file extension

Microsoft ASF Redirector File

Video Files

XCODEPROJ file extension

Xcode Project

Developer Files

PART file extension

Partially Downloaded File

Misc Files

HTM file extension

Hypertext Markup Language File

Web Files