This book is about writing well-designed software. To understand software, we must first have a fundamental understanding of its role in a computer system. Hardware and software cooperate in a com-puter system to accomplish complex tasks. The purpose of various hardware components, and the way those components are connected into networks, are important prerequisites to the study of software development. This chapter first discusses basic computer processing and then begins our exploration of software development by intro-ducing the Java programming language and the principles of object-oriented programming.