Yoghurt or yogurt, less commonly yoghourt, joghurt or yogourt, is a dairy product produced by bacterial fermentation of milk. Any sort of milk may be used to make yoghurt, but modern production is dominated by cow's milk. It is the fermentation of milk sugar (lactose) into lactic acid that gives yoghurt its gel-like texture and characteristic tang. It is often sold in a fruit, vanilla, or chocolate flavour, but can also be unflavoured.