The Mediator EnvirOnment for Multiple Information Sources (MOMIS) aims at constructingsynthesized, integrateddescriptions of the information coming from multiplehe terogeneous sources, in order to provide the user with a global virtual viewof the sources independent from their location and the level of heterogeneity of their data. Such a global virtual view is a conceptualizationof the underlying domain andthen may be thought of as anontology describing the involved sources. In this article wee xplore the framework’s main elements and discuss how the output of the integration process can be exploited to create a conceptualization of the underlying domain.