The results obtained in Section 8.4 have shown that a part of the representation theory of C*-algebras can be generalized to unbounded *-representations if, roughly speaking, the self-adjointness of certain *-representations is assumed. Thus seld-adjoint representations are basic objects in the theory of *-representations of general *-algebras. In this chapter we are concerned with self-adjoint representations of commutative *-algebras.