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

ASP file extension

Active Server Page

Web Files

INI file extension

Windows Initialization File

Settings Files

AI file extension

Adobe Illustrator File

Vector Image Files

3DM file extension

Rhino 3D Model

3D Image Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

TXT file extension

Plain Text File

Text Files

SRT file extension

SubRip Subtitle File

Video Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

DXF file extension

Drawing Exchange Format File

CAD Files

RSS file extension

Rich Site Summary

Web Files

7Z file extension

7-Zip Compressed File

Compressed Files

CSV file extension

Comma Separated Values File

Data Files

MOV file extension

Apple QuickTime Movie

Video Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

PAGES file extension

Pages Document

Text Files