With the invention of unified theories of strong, weak, electromagnetic and gravitational interactions, elementaryparticle physics has entered a very interesting and unusual stage of its development. The end of the 1960s saw the introduction of the Glashow-Weinberg-Salam unification of the weak and electromagnetic interactions. In 1974 came the grand unified theories of the strong, weak and electromagnetic interactions. Two years later we had supergravity, giving us the first hope of unifying all fundamental interactions, including gravitation. The beginning of the 1980s witnessed a renewal of interest in the Kaluza-Klein theories and supergravity in higher-dimensional space-time. Nowadays superstring theory is the leading candidate for the role of “theory of everything.”