Integrating Semantic Web concepts into the domain of e-business is a hot topic. However, most of the efforts spent so far concentrated on the improvement on B2C (business-to-consumer) e-commerce applications, achieved by semantic enrichment of information. With the growing importance of Service Oriented Architectures (SOA) companies started to move into the section of the Electronic Data Interchange (EDI), where applications exchange their business information semi-automatically. This B2B (business-to-business) electronic commerce is driven by aligning the internal business processes of companies to publicly available business processes. Thereby companies often do not consider the economic drivers of their business processes, which leads to incompatibilities between management, administration and technical layers. This chapter covers the two major domains of e-business / e-commerce, namely B2B and B2C. In the first, a model-driven approach towards B2B IT solutions is introduced, covering semantic aspects dealing with business models, business process models, and business document models. In the second application domain, the basic concepts of Semantic Web in the area of B2C electronic commerce are examined using a representative example from the e-tourism domain.