The phenomenology related to the exceptional groups of string theory will be reviewed. A known success of the E6 model is an accurate prediction of the Weinberg angle. Spontaneous symmetry breaking produces scalar and fermion fields that do not belong to the lepton and quark multiplets, and therefore, a description of the standard model is likely to be derived from a group of less dimension. A comparison with theories that contain compact groups, which are subgroups of the ten-dimensional Lorentz group, is given. Following the reduction of a twelve-dimensional theory, governing the ten-dimensional superstring and heterotic string effective actions in ten dimensions, over the coset manifold G2×SU(2)×U(1) / SU(3)×U(1)′×U(1)′′, or eleven-dimensional supergravity over the compact space Mklm, the renormalization group flow of the couplings is found to give the approximate value of $\sin^2\theta_W$ only for a certain ratio of the hypercharge to nonabelian gauge couplings, which is found to require modification at supersymmetric scales. The isometry groups of these coset spaces arise from geometrical considerations, while a unique connection with the larger exceptional group is introduced through the intersection form of the manifold in four dimensions.