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

JS file extension

JavaScript File

Web Files

EXE file extension

Windows Executable File

Executable Files

7Z file extension

7-Zip Compressed File

Compressed Files

TTF file extension

TrueType Font

Font Files

ASX file extension

Microsoft ASF Redirector File

Video Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

ICO file extension

Icon File

System Files

YUV file extension

YUV Encoded Image File

Raster Image Files

SH file extension

Bash Shell Script

Developer Files

SDF file extension

Standard Data File

Data Files

CSV file extension

Comma Separated Values File

Data Files

DOC# file extension

Microsoft Word Document

Text Files

WMA file extension

Windows Media Audio File

Audio Files

CUR file extension

Windows Cursor

System Files

DOCX file extension

Microsoft Word Open XML Document

Text Files