Methods to determine rotamer populations from NMR homo- and heteronuclear vicinal coupling constants are reviewed. Theory and practice related to the elucidation of various gauche and trans limiting coupling constants as key parameters in the characterization of discrete rotational isomers are discussed. Properties and capacities of Karplus-type equations are assessed. Continuous models of rotational isomerism are compared to discrete ones. Principles of the highly specific physicochemical parameters rotamer-specific basicity and rotamer-specific partition coefficient are also described.