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

DDS file extension

DirectDraw Surface

Raster Image Files

CPL file extension

Windows Control Panel Item

System Files

ASF file extension

Advanced Systems Format File

Video Files

H file extension

C/C++/Objective-C Header File

Developer Files

7Z file extension

7-Zip Compressed File

Compressed Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

JSP file extension

Java Server Page

Web Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

PRF file extension

Outlook Profile File

Settings Files

RPM file extension

Red Hat Package Manager File

Compressed Files

AI file extension

Adobe Illustrator File

Vector Image Files

DRV file extension

Device Driver

System Files

MPA file extension

MPEG-2 Audio File

Audio Files

RAR file extension

WinRAR Compressed Archive

Compressed Files