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

CAB file extension

Windows Cabinet File

System Files

COM file extension

DOS Command File

Executable Files

CUR file extension

Windows Cursor

System Files

DOC file extension

Microsoft Word Document

Text Files

GAM file extension

Saved Game File

Game Files

JS file extension

JavaScript File

Web Files

PART file extension

Partially Downloaded File

Misc Files

PCT file extension

Picture File

Layout Files

PL file extension

Perl Script

Developer Files

ROM file extension

N64 Game ROM File

Game Files

SDF file extension

Standard Data File

Data Files

VCXPROJ file extension

Visual C++ Project

Developer Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

3DS file extension

3D Studio Scene

3D Image Files