  The concepts of localizable set, localization of a ring and a module at a
localizable set are introduced and studied. Localizable sets are generalization
of Ore sets and denominator sets, and the localization of a ring/module at a
localizable set is a generalization of localization of a ring/module at a
denominator set. For a semiprime left Goldie ring, it is proven that the set of
maximal left localizable sets that contain all regular elements is equal to the
set of maximal left denominator sets (and they are explicitly described). For a
semiprime Goldie ring, it is proven that the following five sets coincide: the
maximal Ore sets, the maximal denominator sets, the maximal left or right or
two-sided localizable sets that contain all regular elements (and they are
explicitly described).
