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

CRX file extension

Chrome Extension

Plugin Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DOC# file extension

Microsoft Word Document

Text Files

GED file extension

GEDCOM Genealogy Data File

Data Files

HTM file extension

Hypertext Markup Language File

Web Files

ICNS file extension

Mac OS X Icon Resource File

System Files

JAR file extension

Java Archive File

Executable Files

JPG file extension

JPEG Image

Raster Image Files

MAX file extension

3ds Max Scene File

3D Image Files

MSG file extension

Outlook Mail Message

Text Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

TEX file extension

LaTeX Source Document

Text Files

TXT file extension

Plain Text File

Text Files

VOB file extension

DVD Video Object File

Video Files

WPD file extension

WordPerfect Document

Text Files