Abstract: Historically the most popular dark matter candidates have been new elementary particles, such as WIMPs and axions. However Primordial Black Holes (PBHs), black holes formed from over-densities in the early Universe, are another possibility. The discovery of gravitational waves from mergers of ~10 Solar mass black hole binaries by LIGO-Virgo has generated a surge in interest in PBH dark matter. I will overview the formation of PBHs, observational probes of their abundance and the key open questions in the field.