This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book focuses on the design of a series of slug tests, the all-too-often neglected phase of a test program. It describes the pre-analysis processing of response data, a critical step for preparing data for formal analysis and for assessing the appropriateness of the assumptions invoked by the analysis methods. A special emphasis is placed on the processing of data collected with pressure transducers. The book also focuses on issues associated with the performance of slug tests, the most practical aspects of a test program. It describes the primary types of equipment that are used for the measurement and storage of head data. Despite the heavy usage by the environmental industry, the slug test is viewed skeptically by many groundwater scientists and engineers.