Photon-Photon Collisions at LHC

I discuss the possibilities for using the LHC as a photon colliding machine. I will demonstrate that the photon parton density in the proton is currently quite well known and consider the implications for LHC phenomenology. In addition, the colour singlet nature of the photon means that it can readily lead to exclusive or semi-exclusive events, with limited or no extra particle production in the final state. I show how such exclusive processes, in particular in combination with proton tagging measurements, provide a well understood environment in which to test the Standard Model and search for BSM physics.