Transclusion

In computer science, transclusion is the inclusion of a document or part of a document into another document by reference.

For example, an article about a country might include a chart or a paragraph describing that country's agricultural exports from a different article about agriculture. Rather than copying the included data and storing it in two places, a transclusion embodies modular design, by allowing it to be stored only once (and perhaps corrected and updated if the link type supported that) and viewed in different contexts. The reference also serves to link both articles.

Transclusion is usually performed on demand at the time one document referencing another is opened, and is normally automatic and transparent to the end user. The result appears to be a single integrated document, even though its parts were assembled on-the-fly from several separate documents which may have come from different computers located in different places.

The term was coined by hypertext pioneer Ted Nelson in 1982.