Transclusion is the inclusion of part or the whole of one or more works (e.g., text or images) in the rendering (i.e., display) of another work.
It differs from conventional copying in that the main work does not contain a copy of the transcluded works but only a reference (e.g., a hyperlink) to them. The software used to render the work is expected to obtain the transcluded material and incorporate it into the main work.
Transclusion is made possible by hypermedia, which is a retrieval system that enables users to gain or provide access to text, images (both still and moving) and sound via hyperlinks, and it is sometimes used in web sites. For example, a web site about urban design could transclude images of cities that are stored on various servers throughout the world rather than having copies of the images on the same web server as the article.
The most common use of transclusion is advertisements on web pages. Advertisers generally prefer to serve their advertisements directly because it allows them to verify the number of page views themselves rather than having to trust the owners of the sites on which they are displayed.
Transclusion can have the advantage of reducing bandwidth consumption for a site using the transcluded material, particularly in the case of bandiwidth-intensive material such as images and sound. However, this will result in increased bandwidth consumption for the organization serving such material, which may or may not be a problem for it.
Another advantage of transclusion is that it can allow the efficient correction or updating material that is used on multiple web sites.
When using transclusion, it is important (for both ethical and legal reasons) to respect the copyrights of material on other web sites. Thus, where appropriate, proper attribution should be provided for transcluded material.
In addition to HTML (hypertext markup language) and other markup languages, there are several additional technologies that also have the ability to perform transclusion. The most popular of these is PHP (an acronym for PHP Hypertext Preprocessor), which features ease of use and the ability to be embedded directly in HTML code.
Created June 19, 2006.