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

DB file extension

Database File

Database Files

DNG file extension

Digital Negative Image File

Camera Raw Files

DOC file extension

Microsoft Word Document

Text Files

DOC# file extension

Microsoft Word Document

Text Files

INI file extension

Windows Initialization File

Settings Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

M3U file extension

Media Playlist File

Audio Files

ODT file extension

OpenDocument Text Document

Text Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PL file extension

Perl Script

Developer Files

RPM file extension

Red Hat Package Manager File

Compressed Files

SRT file extension

SubRip Subtitle File

Video Files

TTF file extension

TrueType Font

Font Files

WPD file extension

WordPerfect Document

Text Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files