The so-called "dark matter problem" is fundamentally a mass discrepancy. For many types of astrophysical systems, different ways of estimating total mass give different answers. This implies that either there is more mass than what is visible (hence the term “dark matter”), or that something is wrong with the understanding of gravity used to infer the distribution of invisible matter. In this project we surveyed a variety of possible solutions to the dark matter problem. In the end we chose to focus on primordial black holes (PBHs) as a particularly interesting possibility to explore. This presentation will discuss some of the observational reasons for a renewed interest in PBHs, along with scenarios for how they might have formed and how they might be detected.