The Diffuse Gamma-Ray Background (DGRB) is the radiation that remains after the contribution of Galactic gamma-ray emission and of extragalactic resolved sources is subtracted from the total gamma-ray flux. The DGRB collects the radiation produced by all those sources that are not bright enough to be resolved individually. Therefore, it represents an essential tool to study faint gamma-ray emitters, like star-forming or radio galaxies and the exotic Dark Matter.
I will review our current knowledge of the nature of the DGRB, presenting the strategies that have been proposed to study it. I will focus, in particular, on how it is possible to derive some constraints on the emission associated to Dark Matter, by reconstructing the composition of the DGRB. (host: Sanchez-Conde)