Roby-Gould Bond Indices

The concept of a bond index in chemistry is reviewed from a philosophical and historical perspective in order to place the Roby-Gould bond indices into context with other approaches. The level adopted is suitable for those interested in using such methods. The dual relationship between atoms and bond indices is stressed. Roby-Gould bond indices and its visual representation via the bond dial diagram are systematically reviewed for increasingly complex molecules, and compared with chemical expectations. A road map for future development is outlined.