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

ACCDB file extension

Access 2007 Database File

Database Files

ASX file extension

Microsoft ASF Redirector File

Video Files

CFM file extension

ColdFusion Markup File

Web Files

CPP file extension

C++ Source Code File

Developer Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DOC file extension

Microsoft Word Document

Text Files

DOC# file extension

Microsoft Word Document

Text Files

GADGET file extension

Windows Gadget

Executable Files

HTM file extension

Hypertext Markup Language File

Web Files

JAR file extension

Java Archive File

Executable Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

RPM file extension

Red Hat Package Manager File

Compressed Files

SLN file extension

Visual Studio Solution File

Developer Files

TXT file extension

Plain Text File

Text Files