This chapter discusses information systems concepts and the evolution of information technology. It describes how information systems have developed from early transaction processing systems to today's enterprise systems and knowledge management tools. The chapter also outlines different ways of classifying information systems, such as by organizational level or breadth of support. It explains key computing environment models including legacy systems, client/server architecture, and distributed computing. The chapter provides an overview of information systems concepts and issues to help readers understand the role of IT in organizations.