This paper proposes the use of ontologies representing domain and linguistic knowledge for guiding natural language (NL) communication on the Web contents. This
proposal deals with the problem of accessing and processing the Web data required to answer user consults. Concepts and communication acts are represented in
the conceptual ontology (CO). Domain-restricted grammars and lexicons are obtained automatically by adapting the general linguistic knowledge to cover the
communication acts for a particular domain. The use of domain-restricted grammars and lexicons has proved to be efficient especially when the user is guided in
introducing the NL queries. Once the query has been processed, the system fires the appropriate wrappers to extract the data from the Web. The domain concepts
described in the CO provides a unifying framework to represent the knowledge obtained from the various Web sources.