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

PY file extension

Python Script

Developer Files

MOBI file extension

Mobipocket eBook

eBook Files

TIF file extension

Tagged Image File

Raster Image Files

EXE file extension

Windows Executable File

Executable Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

XML file extension

XML File

Data Files

TOAST file extension

Toast Disc Image

Disk Image Files

JPG file extension

JPEG Image

Raster Image Files

ASF file extension

Advanced Systems Format File

Video Files

MP4 file extension

MPEG-4 Video File

Video Files

CSS file extension

Cascading Style Sheet

Web Files

WMA file extension

Windows Media Audio File

Audio Files

RTF file extension

Rich Text Format File

Text Files

VCXPROJ file extension

Visual C++ Project

Developer Files

7Z file extension

7-Zip Compressed File

Compressed Files