In particle physics, the Glashow–Iliopoulos–Maiani (GIM) mechanism is allegedly the mechanism through which flavour-changing neutral currents (FCNCs) are suppressed in loop diagrams. It also explains why weak interactions that change strangeness by 2 (ΔS = 2 transitions) are suppressed, while those that change strangeness by 1 (ΔS = 1 transitions) are allowed, but only in charged current interactions. It is named after physicists Sheldon Glashow, John Iliopoulos and Luciano Maiani.