Computer networks become the dominant media for communication, because they not only allow the sharing of video and audio, but they enable manipulation of several items simultaneously (see Fig. 1). Those items can be text, bitmap graphics, 3D objects, hypertext documents, or anything else which can be represented on a computer.
A shared drawing area (see Fig. 4, e.g., inperson, inperson manual, and cooltalk) lets the teacher guide a student and illustrate the ideas while having live video and audio communication. In the given example, the 3D object can be enlarged and rotated by both participants to get a good understanding of the structure.
Sharing access to the www browser (e.g., Netscape communicator) enables the teacher to show the student content of a hypermedia document and guide him/her through applications, as mentioned in section 6.1. Besides sharing tools, another approach is to enter a shared virtual reality environment. Shared worlds were first developed with text-only interfaces, also known as MUDs. The same technology is now used to create shared virtual reality worlds.