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

AZW file extension

Amazon Kindle eBook File

eBook Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

M4A file extension

MPEG-4 Audio File

Audio Files

7Z file extension

7-Zip Compressed File

Compressed Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

INDD file extension

Adobe InDesign Document

Layout Files

SRT file extension

SubRip Subtitle File

Video Files

RPM file extension

Red Hat Package Manager File

Compressed Files

DEM file extension

Video Game Demo File

Game Files

THM file extension

Thumbnail Image File

Raster Image Files

PDF file extension

Portable Document Format File

Layout Files

CBR file extension

Comic Book RAR Archive

Compressed Files

PY file extension

Python Script

Developer Files

WMA file extension

Windows Media Audio File

Audio Files

PDB file extension

Program Database

Database Files