In this paper we show that the identity function e of a generalized ring R is a generalized ring homomorphism if e(x + y) = e(x) + e(y), for all x, y e R. Moreover, we show that if R is a generalized ring with an identity, then e is a generalized ring homomorphism. Properties of identities and identity mappings of generalized rings are considered. A method for constructing a new generalized ring with an identity via a given quotient generalized ring with an identity, is presented. Second isomorphism theorem and third isomorphism theorem for M-rings are proved.