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

CPL file extension

Windows Control Panel Item

System Files

CSR file extension

Certificate Signing Request File

Web Files

DXF file extension

Drawing Exchange Format File

CAD Files

IBOOKS file extension

Multi-Touch iBook

Data Files

ICNS file extension

Mac OS X Icon Resource File

System Files

JAVA file extension

Java Source Code File

Developer Files

JSP file extension

Java Server Page

Web Files

M file extension

Objective-C Implementation File

Developer Files

MSI file extension

Windows Installer Package

Misc Files

PHP file extension

PHP Source Code File

Web Files

PIF file extension

Program Information File

Executable Files

PPT file extension

PowerPoint Presentation

Data Files

UUE file extension

Uuencoded File

Encoded Files

VCD file extension

Virtual CD

Disk Image Files