1. A method performed in a system comprising user navigable nodes, documents attached to the user navigable nodes, keywords associated with the user navigable nodes and having search and navigation capability that allows users to move from node to node via links between the nodes and make selections when at individual nodes, the method comprising, at a user navigable node within the system: receiving an input from a user; determining that the input contains an unknown word; subsequent to the determining, navigating through the system to a current node from the user navigable node based upon at least one additional input from the user that was provided while at the user navigable node; presenting at least one response to the user based upon the documents attached to the current node resulting from the navigation; and following presentation of the at least one response, learning one or more associations between the unknown word and one or more keywords from the documents attached to the current node, such that a direct relationship is formed between the unknown word and the one or more keywords.