The invention of novel and improved catalysts has a valuable impact on human activities and on our planet. Efficient catalysts are expected to be stable, active, and selective. In the past, the development of new catalysts has mainly depended on trial and error, a laborious and time-consuming approach. Nowadays, the mechanistic details of numerous important chemical reactions have been unraveled, and this information is useful for intelligently design novel catalysts. Thus, all the efforts devoted to facilitating a deep understanding of intricate catalytic mechanisms and to the preparation of novel catalysts relying on this are priceless. Chemists must set up adequate strategies, merging experimental and computational knowledge and abilities toward tuning the performance of molecules that might be successful in the lab. The contributions in this book collection are some examples of this modern chemical design.