Signatures of and constraints on Primordial Black Holes as dark matter

Abstract: will review the Primordial Black Hole (PBH) hypothesis for explaining the dark matter in the universe. I will focus on the peculiar ‘asteroid mass range’ where this possibility remains viable, discussing a number of signatures (Hawking radiation, micro-lensing, transit in stars) that have been proposed to search for them, and present current constraints. I will conclude highlighting some perspectives for the foreseeable future.