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

C file extension

C/C++ Source Code File

Developer Files

CUR file extension

Windows Cursor

System Files

DOC# file extension

Microsoft Word Document

Text Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

JS file extension

JavaScript File

Web Files

MP3 file extension

MP3 Audio File

Audio Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PART file extension

Partially Downloaded File

Misc Files

RPM file extension

Red Hat Package Manager File

Compressed Files

TEX file extension

LaTeX Source Document

Text Files

VCD file extension

Virtual CD

Disk Image Files

VOB file extension

DVD Video Object File

Video Files

XCODEPROJ file extension

Xcode Project

Developer Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files