This introduction collects 17 innovative approaches to engineer novel and improved proteins for diverse applications in biotechnology, chemistry, bioanalytics and medicine. As such, key developments covered in this reference and handbook include de novo enzyme design, cofactor design and metalloenzymes, extremophile proteins, and chemically resistant proteins for industrial processes. The editors integrate academic innovations and industrial applications so as to arrive at a balanced view of this multi-faceted topic. Throughout, the content is chosen to complement and extend the previously published two-volume handbook by the same editors, resulting in a superb overview of this burgeoning field.