Modern economies depend on innovation in services for their future growth. Service innovation increasingly depends on information technology and digitization of information processes. Designing new services is a complex matter, since collaboration with other companies and organizations is necessary. Service innovation is directly related to business models that support these services, i.e. services can only be successful in the long run with a viable business model that creates value for its customers and providers. This book presents a theoretically grounded yet practical approach to designing viable business models for electronic services, including mobile ones, i.e. the STOF model and - based on it - the STOF method. The STOF model provides a 'holistic' view on business models with four interrelated perspectives, i.e., Service, Technology, Organization and Finance. It elaborates on critical design issues that ultimately shape the business model and drive its viability.