Although context-awareness is a central paradigm for the implementation of ubiquitous systems, it still lacks adequate representation models, methods and tools that support the development of such systems. Particularly, in order to secure interoperability and allow device interaction, software applications are required to provide unambiguous data and device representation models. In this paper we argue in favor of the use of formal ontology as the tool to formalize the notion of context, describe the interplay between systems and environments and, ultimately, enable verification. Ontologies allow machines to process and integrate devices intelligently, enable quick and accurate search, facilitate communication between a multitude of heterogeneous devices and enable reasoning [22].