Hypermedia - Hypertext is a subcategory of hypermedia. Hypermedia allows linking of graphics, sound and text. The web is a partial hypermedia system as it supports graphical hyperlinks and links to sound and video files. More advanced hypermedia systems allow objects in computer videos to be hyperlinked. 

A big glossary of terms concerning hypermedia is at:
www.weihenstephan.de/~schlind/genglos.html.

See the Interactive Television Institute.