Communication is virtually impossible when interlocutors lack the ability to negotiate meanings. The intended semantics of the language used by a sender should be perceived and mastered by its receiver. Web sites are complex interactive communication systems speaking two languages: the one of the "content" and the one of the "interface". The latter consists of the set of "signs" (i.e. labels, icons, words, etc....) used to provide interaction to users.

The paper proposes W-SIDE, a method (based upon ontologies and semiotics) for analyzing the quality of the interface language, and its impact upon users. Case studies (including user testing) are also discussed.