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

DOC file extension

Microsoft Word Document

Text Files

7Z file extension

7-Zip Compressed File

Compressed Files

AI file extension

Adobe Illustrator File

Vector Image Files

GZ file extension

Gnu Zipped Archive

Compressed Files

TEX file extension

LaTeX Source Document

Text Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

LOG file extension

Log File

Text Files

H file extension

C/C++/Objective-C Header File

Developer Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

SRT file extension

SubRip Subtitle File

Video Files

ASP file extension

Active Server Page

Web Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

SAV file extension

Saved Game

Game Files

DEM file extension

Video Game Demo File

Game Files

NES file extension

Nintendo (NES) ROM File

Game Files