In this paper we demonstrate why executives and academics should consider thinking about e-business models. We show that the business model concept is an interesting tool for understanding, designing, sharing, measuring, changing and even simulating businesses. Based on an extensive review of e-business and business model literature we develop an e-business model ontology. This ontology defines the concepts in e-business models and the relationships between them and shall be the foundation for a variety of management tools that facilitate business decisions. Our e-business model ontology outlines what value a company offers to which customer segments. It describes the architecture of the firm and its network of partners for creating, marketing and delivering value and relationship capital, in order to generate profitable and sustainable revenue streams.