Personalized online tourism services play a crucial role for tourists. In order to deliver adequate information, a semantic matching between tourism services and user context is needed. In the phase of trip planning, the essential user context comprises primarily user preferences and interests, while during the trip location and time context are added. While being on the move, unexpected events might force tourists to completely reschedule their travel plan and look for alternatives. In order to facilitate semantic matching between alternative touristic sites and user context, a specific vocabulary for the tourism domain, user type, time and location is needed. We demonstrate in this project that existing tourism ontologies can hardly fulfill this goal as they mainly focus on domain concepts. Based on the evaluation of existing tourism ontologies we developed a core Domain Ontology for Travel and Tourism (cDott). We demonstrate interesting concepts of the cDOTT vocabulary, such as classifying travelers into tourist types and match them to appropriate activities (e.g., bungee jumping). The goal of this project is to provide an alternative approach for covering the semantic space of tourism through the integration of modularized ontologies, such as user, W3C Time or W3C Geo, that center around a core domain ontology for the tourism sector.