Product configuration is the activity of customizing a product to meet the individual needs of a particular customer. The goal is to offer such a product at a similar price as in mass production and to transparently give the customer all relevant information, e.g., about environmental impact. This requires appropriate tools, i.e. configurators, for specifying the product variety and recommending individual solutions. This chapter introduces the most important concepts and terms around product configuration to lay a solid basis for the book. The historical development of the subject matter is outlined briefly, various degrees of individualization are discussed, important stakeholders are listed, and the importance and benefits of mass customization and product configuration for modern manufacturing are motivated. In the end of the chapter, we introduce the configurable folding bike product that will serve as running example throughout the book.