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

HTM file extension

Hypertext Markup Language File

Web Files

7Z file extension

7-Zip Compressed File

Compressed Files

M file extension

Objective-C Implementation File

Developer Files

PRF file extension

Outlook Profile File

Settings Files

APK file extension

Android Package File

Executable Files

3DM file extension

Rhino 3D Model

3D Image Files

PPT file extension

PowerPoint Presentation

Data Files

H file extension

C/C++/Objective-C Header File

Developer Files

VCXPROJ file extension

Visual C++ Project

Developer Files

AIF file extension

Audio Interchange File Format

Audio Files

CAB file extension

Windows Cabinet File

System Files

EXE file extension

Windows Executable File

Executable Files

THM file extension

Thumbnail Image File

Raster Image Files

CS file extension

Visual C# Source Code File

Developer Files

BIN file extension

Binary Disc Image

Disk Image Files