Superconductivity, the ability of certain materials to conduct electricity withno resistance whatsoever, has fascinated scientists since its discovery byKammerlingh-Onnes in 1911. While much has been understood, the questionof predicting which materials will become superconducting, and at whattemperatures, remains one of the grand challenges of modern materialstheory. This talk will outline the evolution of our understanding as the subjecthas progressed from its primitive beginnings through the ''bronze age''marked by the 1986 discovery of high temperature superconductivity incopper-oxide compounds to the present-day ''iron age'' of the Fe-As basedsuperconducting materials. The current status of the theory of the origin ofsuperconductivity will be described.