In this introductory chapter, we discuss mammalian cell culture for the production of therapeutic proteins in the broader context of biotechnology and, in particular, of the biopharmaceutical industry. We begin with a short retrospect on the history of cell cultures for bioproduct manufacturing and eventually introduce recombinant technology, in order to appreciate how the present standards were established. An overview of the current market on recombinant therapeutic proteins provides some important understanding of the industry challenges to come and the contribution that continuous manufacturing can provide. We then introduce the various bioreactor types that can be used in this area and indicate the challenges to be faced for their development, design, and operation. The objective here is to put all these aspects in the right perspective and address the reader to the chapters where each of them is specifically treated in the monography.