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

CER file extension

Internet Security Certificate

Web Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

DTD file extension

Document Type Definition File

Developer Files

JS file extension

JavaScript File

Web Files

MDB file extension

Microsoft Access Database

Database Files

MPA file extension

MPEG-2 Audio File

Audio Files

PAGES file extension

Pages Document

Text Files

PRF file extension

Outlook Profile File

Settings Files

RSS file extension

Rich Site Summary

Web Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

TARGZ file extension

Compressed Tarball File

Compressed Files

VCD file extension

Virtual CD

Disk Image Files

VCXPROJ file extension

Visual C++ Project

Developer Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

3DS file extension

3D Studio Scene

3D Image Files