Archie is an application of the Prospero protocol, but for people without Prospero clients, there is also the possibility to log into a machine running an Archie database and give commands inside a restricted shell. Many machines around the world act as WWW servers, meaning that they have a collection of hyper-documents that they will transfer on request. Inside a document there may be references to other documents, also in the form of URL's. Documents need not be text. The client determines the range of formats that it recognizes.
Some clients are smarter than others.
Typically, WWW clients know a number of protocols, such as FTP, Gopher, NNTP and, of course, HTTP . A list of WWW clients is also available from CERN in Geneva. At least on a Unix system that is not difficult to do. WWW supports format negotiations between server and client for case when information is available in several formats. Interactive forms are possible with a range of buttons, radio-buttons, and input fields.