Title: Colliding Light


At LEP2 the process with the largest cross section is that of two photons (radiated by the beam electrons and positrons) interacting hadronically. This offers a unique chance to test and extend our knowledge of the hadronic properties of this very fundamental particle. I will introduce the processes involved and describe the measurements used to study them: what they teach us in themselves, what the implications are for present hadron and future linear colliders, and what we can expect to learn in the future.