Oases (singular oasis) are fertile areas of plants and water in the desert. Fictional oases are often places of refuge, mystery, and hidden danger. As locations where water can be found in the midst of desert dunes, these sites attract all manner of other elements that worldbuilders can explore. Oases may contain springs, lakes, or rivers. They may be sites of desert towns, cities, or temples. If sufficiently isolated amidst a sand sea, they may contain hidden civilizations. They may be the sites of ruins. They may be stops in a trade route. Oases may be real, but they also may be nothing but a mirage.