Accomplishing the evolving objectives of a software project in time and budget on a long-term basis is a difficult undertaking. In this opening chapter, we're going to explain why unit testing can play a vital role in meeting these demands. We'll illustrate the positive influence on the defect rate, code quality, development pace, specification density, and team morale. All that makes it worthwhile to acquire a broad understanding of the various testing techniques. To get started, you'll learn to arrange our tool set around JUnit and organize our project infrastructure properly. You'll be familiarized with the definition of unit tests and the basics of test-driven development. This will prepare us for the following chapters, where you'll come to know about more advanced testing practices.