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

AIF file extension

Audio Interchange File Format

Audio Files

AZW file extension

Amazon Kindle eBook File

eBook Files

DTD file extension

Document Type Definition File

Developer Files

EPUB file extension

Open eBook File

eBook Files

GZ file extension

Gnu Zipped Archive

Compressed Files

HTML file extension

Hypertext Markup Language File

Web Files

JAR file extension

Java Archive File

Executable Files

PAGES file extension

Pages Document

Text Files

PDB file extension

Program Database

Database Files

PRF file extension

Outlook Profile File

Settings Files

SYS file extension

Windows System File

System Files

TORRENT file extension

BitTorrent File

Misc Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

WSF file extension

Windows Script File

Executable Files

XML file extension

XML File

Data Files