Gamma-ray signatures of Dark Matter

I review the ways in which Dark Matter can produce gamma-rays (and lower energy photons) and I apply the considerations to three specific examples: the tests of multi-TeV pure-WIMP candidates based on high energy gamma-rays from the Galactic Center or dwarfs, the importance of bremsstrahlung emission for light DM, the updated constraints on DM from all-sky radio surveys of the Milky Way.