The long-held notion of a bone-dry Moon was challenged in 2008, with the detection of water in some of the Apollo samples. Since then, lunar scientists have sought to understand how much water is in the Moon, where it is, and where it comes from. In this web focus, we present an overview article, research papers and opinion pieces that evaluate the evidence for water in the lunar interior and on the lunar surface and discuss its origin — whether it was added by cometary impacts, implanted by the solar wind, or indigenous to a Moon that may not, in fact, have formed dry.