This workshop aims to discuss the phenomenological implications of Primordial Black Holes (PBH), such as their possible relationship with dark matter origin, neutrino mass, the baryon asymmetry, inflation, their theoretical aspects and origin and the possible multi-messenger detection and the experimental state-of-the-art. Recently, the interest in PBHs from the physics community is growing because they can provide an alternative explanation of some of the major problems of the Standard Model. We know that Black Holes can merge or evaporate (according to the seminal paper by Hawking), generating gravitational waves, fluxes of Dark Matter, and standard model particles. Therefore, different experimental indirect searches can possible exploit the multi-messenger approach. This workshop will be co-organized by two main institutions, namely the University of Naples Federico II and the University of Durham.