Prompt photons are both signatures and backgrounds for new physics and Higgs searches. From an experimental point of view, searches with final state photons have many advantages: photons couple to any particles with electric charge; they do not suffer a sensitivity loss from branching ratios; photon energy and direction are well measured. I will present results of a search for new physics with two photons and large missing transverse energy and a study of the prompt diphoton production in the context of Standard Model. I will also pay a special attention to experimental techniques.