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

BAK file extension

Backup File

Backup Files

BIN file extension

Binary Disc Image

Disk Image Files

DLL file extension

Dynamic Link Library

System Files

ICS file extension

iCalendar File

Misc Files

JAVA file extension

Java Source Code File

Developer Files

KML file extension

Keyhole Markup Language File

GIS Files

LNK file extension

Windows File Shortcut

System Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

SLN file extension

Visual Studio Solution File

Developer Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

TEX file extension

LaTeX Source Document

Text Files

TOAST file extension

Toast Disc Image

Disk Image Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

3GP file extension

3GPP Multimedia File

Video Files