The use of hypermedia as an instructional medium is growing rapidly with developments and enhancements in instructional and computing technologies. Much of the popularity of the medium is derived from its capacity to convey large amounts of information to learners in structured and associated ways which promote student centred and independent learning. Recent developments in multimedia technologies and software, and enhanced networking facilities through the Internet, have led to new and exciting opportunities for hypermedia systems development. This paper provides an overview of the potential of hypermedia as an instructional medium and discusses research that has investigated learning outcomes. It provides an overview of instructional design considerations to guide developers and designers of hypermedia systems.Hypertext, or hypermedia as it is more commonly called today, is an instructional medium which appears to hold considerable promise for teaching and learning. It manifests itself in many forms, often with quite disparate appearances and capabilities. For example, the majority of CD ROM based information systems such as electronic encyclopedia are examples of hypermedia systems as are the majority of instructional materials delivered on the World Wide Web. Although different in appearance, scope and form, the unifying characteristics of these computer based materials are the structure they embrace and the purpose they serve.Structure. Hypermedia materials are comprised of multiple separate information nodes. These information nodes contain various media forms such as text, sound, graphics and movies either individually or combined. The structure of a hypermedia system enables users to access information from the nodes in a non linear way. Users are able to progress from one node to the next using links supplied by the system designer. The two Oliver and Herrington 9 fundamental units in a hypermedia system are the information nodes themselves and the links that connect them.The links in a hypermedia system create associations between the nodes. Links are usually provided only between nodes that are associated or semantically related. The structure of a hypermedia system is often compared to the human mind which also stores information as discrete nodes with links between those that are related and/or associated.Purpose. Hypermedia materials are usually designed as information delivery systems. In this role they serve an instructional purpose. While some systems are designed as information sources within which the user is free to browse, others constrain the user to follow paths through the stored information. Such paths are set by the instructional designer and lead the user through the information in the same way as a book presents content to a reader. As purveyors of information, hypermedia systems provide many advantages over paper based forms. They are very flexible and powerful in the way in which information is accessed and provide access to multiple media forms.Nature. Hypermedia systems employ ma...