Hypertext vs Hypermedia
Hypertext is basically the similar as regular text - it can be stored, read, searched, or edited - with a significant exception: hypertext having connections within the text to other documents.
Hypermedia documents having links not only to other pieces of text, but also to other forms of media - sounds, images, and movies. Images themselves can be selected to link to sounds or documents. Here are some World Wide Web is an open hypermedia system.