In this book we need to develop a general understanding of business firms to enable strategic IS/IT planning. We will present the resource-based theory of the firm, the activity-based theory of the firm and the firm in terms of its value configuration. An understanding of firm theories and value configurations is important to later discussions of the topics in the book. The resource-based theory is applied to understand resources needed for e-business, sourcing, and governance. An important resource is knowledge in terms of know-what, know-how and know-why.