Specialization is the separation of tasks within a system. In a multicellular creature, cells are specialized for functions such as bone construction or oxygen transport. In capitalist societies, individual workers specialize for functions such as building construction or gasoline transport. In both cases, specialization enables the accomplishment of otherwise unatainable goals. It also reduces the ability of individuals to survive outside of the system containing all of the specialized components.
Additional meaning of Specialization (functional):
Adam Smith described economic specialization in his classic work, The Wealth of Nations.