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

DXF file extension

Drawing Exchange Format File

CAD Files

HTML file extension

Hypertext Markup Language File

Web Files

ICO file extension

Icon File

System Files

ISO file extension

Disc Image File

Disk Image Files

JSP file extension

Java Server Page

Web Files

M4A file extension

MPEG-4 Audio File

Audio Files

MSI file extension

Windows Installer Package

Misc Files

PRF file extension

Outlook Profile File

Settings Files

RTF file extension

Rich Text Format File

Text Files

UUE file extension

Uuencoded File

Encoded Files

VOB file extension

DVD Video Object File

Video Files

WMV file extension

Windows Media Video File

Video Files

3DS file extension

3D Studio Scene

3D Image Files

3G2 file extension

3GPP2 Multimedia File

Video Files