Publisher Summary This chapter introduces pattern recognition as the scientific discipline with the goal of classification of objects into a number of categories or classes. The chapter discusses the basic philosophy and methodological directions in which the various pattern recognition approaches have evolved and developed. Pattern recognition is an integral part of most machine intelligence systems built for decision making. Machine vision is an area in which pattern recognition is of importance. A typical application of a machine vision system is in the manufacturing industry, either for automated visual inspection or for automation in the assembly line. Character recognition is another important area of pattern recognition, with major implications in automation and information handling. Computer-aided diagnosis is an application of pattern recognition, aimed at assisting doctors in making diagnostic decisions. The chapter outlines various other areas in which pattern recognition finds its use. The chapter also explains the concept of supervised, unsupervised, and semisupervised learning, and concludes with a brief discussion on the contents of other chapters.