What's the dark matter made of? Do we have any idea of the kind of particle that should constitute ~85% of the matter content of the Universe? In this talk, I will briefly explain the properties that such a particle might have and will present some of the proposed candidates that arise from beyond the Standard Model of particle physics. Next stop will be to give an overview of the present status of dark matter searches, mainly focusing on gamma-rays. There is a tremendous effort currently ongoing that involves an impressive battery of experiments both at the lab and observatories around the world.

In a second part,  the importance of N-body cosmological simulations for the understanding of how dark matter halos form and evolve from the early Universe will be discussed. At this point, some problems arise that it's worth mentioning and that will hopefully lead to debate.