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

LUA file extension

Lua Source File

Developer Files

TTF file extension

TrueType Font

Font Files

WSF file extension

Windows Script File

Executable Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

ZIPX file extension

Extended Zip File

Compressed Files

PY file extension

Python Script

Developer Files

CLASS file extension

Java Class File

Developer Files

VCXPROJ file extension

Visual C++ Project

Developer Files

XCODEPROJ file extension

Xcode Project

Developer Files

M file extension

Objective-C Implementation File

Developer Files

WMV file extension

Windows Media Video File

Video Files

7Z file extension

7-Zip Compressed File

Compressed Files

SDF file extension

Standard Data File

Data Files

SITX file extension

StuffIt X Archive

Compressed Files

IFF file extension

Interchange File Format

Audio Files