Biocatalysis has meanwhile become an essential tool in the chemical industry and is the central part of biotechnology, defined by the European Federation of Biotechnology already in 1988 as “the integration of natural sciences and organisms, cells, parts thereof, and molecular analogues for products and services.” As to the industrial application, biocatalysis is the core of industrial biotechnology, also known as white biotechnology; “white” stands for the positive impact on the environment associated with the use of biocatalysts as enzymes or whole cells in chemical processes as an alternative to chemical catalysts. Drivers of this development are the big challenges resulting from concerns about global climate change and the need for an assured energy supply. These aspects are discussed in Chapter 1 together with an overview of the many areas of daily life where biocatalysts are already employed.