Key features common to all RQMs include: the prediction of antimatter, spin magnetic moments of elementary spin '"`UNIQ--templatestyles-00000011-QINU`"' 1 ⁄ 2 fermions, fine structure, and quantum dynamics of charged particles in electromagnetic fields. The key result is the Dirac equation, from which these predictions emerge automatically. By contrast, in non-relativistic quantum mechanics, terms have to be introduced artificially into the Hamiltonian operator to achieve agreement with experimental observations.