In the study of finite groups, we have proved several results using the concept of a normal subgroup, quotient construction and induction on the group order. Homomorphic images of groups are identified with quotient groups with the help of the kernel of the homomorphism which is a normal subgroup. The role of normal subgroups in groups is played by ideals in rings. The concepts of ideal and quotient rings are important in the structure theory of rings. A special kind of subrings, which are most suitable (ideal) for the study of the structure of rings, are popularly called ideals.