Abstract
The term “hypertext ” describes the electronic representation of text that takes advantage of the random access capabilities of computers to overcome the strictly sequential medium of print on paper. "Hypermedia ” extends the nonlinear representation and access to graphics, sound, animation, and other forms of information transfer. The term “hyperdocument” is used to refer to the actual text, lesson, or product. Two key features o f any hyperdocument are nodes and links. There are three main characterictics of hypermedia systems that have great potential for learning and teaching. First, hypermedia systems allow huge collections of information in a variety of media to be stored in extremely compact forms and accessed easily and rapidly. Second, hypermedia is an enabling rather than a directive environment, offering unusually high levels of learner control. Third, hypermedia offers the potential to alter the roles of teachers and learners and the crucial interactions between them. Good teachers always learn from their students, and hypermedia provides an opportunity to facilitate and formalize the human-human interaction that is central to effective teaching and learning. Besides, it supports learning materials that offer freedom of choice to the learners. The characteristics of hypermedia that excite educators also present theoretical and technical problems. These problems are: hypermedia as an object of instruction (literacy), hypermedia as an environment for learning, and hypermedia as an environment for teaching.