This paper summarizes the research efforts devoted over the years to the understanding of the origin and evolution of brines in the Dead Sea basin. These brines are characterized by a unique Ca-Chloride composition, which evolved from interaction of evaporated seawater filling the late Neogene Sedom lagoon with the Cretaceous carbonate rocks exposed at the basin-bounding escarpments. Following the disconnection of the lagoon from the open sea and the development of inland lakes, the composition of the ancient Sedom brine changed due to precipitation of evaporites and addition of salts from incoming fresh water. Relative to highly evaporated seawater, these processes led to enrichment of the brines in Cl, Br, Mg, Ca, and K and depletion in Na and SO₄. The modern Dead Sea, representing a recent product of these evolutionary processes, derived its ingredients from residual brines that remained after the desiccation of the late Pleistocene Lake Lisan, from incoming fresh water, and from saline springs that emerge along the western shores of the Dead Sea. Similar sources probably dictated the composition of the Pleistocene lakes (Amora, Lisan), though their relative contribution changed through time, reflecting the control of climate on the hydrological system (e.g., the activity of saline springs).