File association

A file association associates a file with an application capable of opening that file. More commonly, a file association associates a class of files (as determined by their filename extension, such as .txt) with a corresponding application such as a text editor.

Associations and verbs

A single file extension may have several associations for performing various actions, also known as verbs. Some of the common verbs are:

• open to open a file
• edit to open a file for editing
• print to print a file

A picture, for example, may be associated with these verbs so that open opens the picture in an image viewer, edit opens up an image editing program and print sends the picture to a printer.

Implementations

Most operating systems support file associations in some form or the other. For example, opening a file from a file manager usually invokes the open verb in order to open the file with its associated application. Additional actions such as print are usually accessed via a right-click context menu. A mechanism for modifying associations is also usually present. (such as the Open With option in Microsoft Windows)

• The Microsoft Windows series of operating systems, beginning with Windows 95 supports file extension-based associations. Associations are stored in registry as sets of verbs for each file extension. Older versions supported open associations stored in WIN.INI.
• Linux-based GUIs, such as KDE and GNOME, support MIME type-based associations. For example, the MIME type text/plain might be associated with a text editor.
• Classic Mac OS used type codes and creator codes to associate each file with its corresponding application, regardless of file extension. The more recent Mac OS X also supports file extension-based associations.

See also

• File format
• Filename extension

Further reading

• Verbs and File Associations in Microsoft Windows
• File Associations in KDE