In 1949 P. A. M. Dirac introduced three representations for formulating relativistic quantum mechanics that are distinguished by having the largest interaction-independent subgroups of the Poincare group. The light front representation has the largest interaction-independent subgroup. It is especially useful treating electro-weak probes of strongly interacting systems. Among its many advantages are the triviality of the light front vacuum, the absence of Wigner rotations on boosts, and the irreduciblity of fields restricted to a light front. I discuss properties of both light front quantum mechanics and quantum field theory and highlight some of the differences with the familiar "instant'' representations.