The ability to backtrack complements the history mechanism. This mechanism records in a meaningful way all the previous visited nodes. Navigation - Bookmarks, Landmarks Bookmarks act a general signs to orient the hypermedia user. The difference between histoty lists and bookmark lists is that a node is inserted in the bookmark list only if the user wants to do so. This condition means that bookmark lists are smaller and thus more manageable than history lists.
Bookmarks correspond to landmark knowledge in psychology cognitive map theory of navigation.
Navigation - Paths Paths is a mechanism for allowing the author to impose a sequence. Path has been introduced as a mechanism for solving navigation problems. The expressive power of apath is determined both by the sequencing model and the characteristic of the entities that can apear along the path. The notion of paths is based on the programming paradigm. Zellweger has described the concept of a path in order to eliminate the influence of link concept in basic hypermedia model.