Introduction to NHCs, synthesis, electronic and steric properties; The various modes of action of NHCs in organocatalysis; NHC-catalyzed umpolung of aldehydes: The benzoin reaction; Acyl anion addition to Michael acceptors: The Stetter reaction; NHC-catalyzed generation of homoenolates and related chemistry; NHC-catalyzed cascade processes for carbocycles and heterocycles synthesis; Oxidative NHC-catalysis; Acyl anion free NHC-organocatalysis; Dual-activation in NHC-catalysis; alpha, beta-unsaturated acylazolium generation using NHCs and addition of bisnucleophiles; Non-umpolung transformations in NHC-catalysis; NHC-catalyzed reactions involving saturated acylazoliums; NHC-catalyzed transformations of acid derivatives; Umpolung of Michael acceptors, alkyl halides and imines; Polymerization reactions catalyzed by NHCs; (Dynamic) Kinetic resolution and Desymmetrization reactions using NHC-catalysis; Application of NHCs in Natural products and biologically active compounds synthesis