Thistextdevelopsacomprehensivetheoryofprogramminglanguagesbasedontypesystemsandstructuraloperationalsemantics.Languageconceptsarepreciselydefinedbytheirstaticanddynamicsemantics,presentingtheessentialtoolsbothintuitivelyandrigorouslywhilerelyingononlyelementarymathematics.Thesetoolsareuse