Although sulfides are mostly not rock-forming minerals, they play a fundamental role in deciphering most of the processes occurring on the planet Earth. Currently, ~600 sulfide minerals are reported in the official IMA-CNMNC List of Mineral Names, accounting for ~10% of the entire mineral kingdom known to date. Furthermore, other minerals contain significant amounts of sulfur substituting Se, Te, or other elements. Our intent here is to present the state of the art of all sulfides by providing an overview of their compositions, crystal structures, and occurrences. Moreover, a review on transition minerals between sulfides and oxides and between sulfides and halides is given.