The main purpose of this introductory chapter is to: (i) familiarize non-experts in the field with this type of catalysis, and (ii) draw the attention of experts to related and complementary fields of which a basic knowledge may be necessary for a good understanding of this type of catalysis. More specifically, we intend to: (i) introduce the key aspects of catalysis with supported metal single-atom catalysts, (ii) discuss the drawing together of closely aligned topics, and (iii) acknowledge the challenges and possible opportunities around the area.