Sand is one of two materials (the other being gravel,) that is affected by gravity and is very weak and easily destroyed making it easy to mine. Sand will fall if there are no blocks below it, and will continue to fall until it collides with another object, so even torches can hold it up in a desired place. When sand falls into the layer it can drain your health and thus kill you if you don't move away. Sand can also be used to create the transparent block, glass by heating it using a furnace. Sands can also be used as it is to make structures, namely a sand castle or house. They are usually found beside ponds, sea shores or any water body.
Related ThreadsSand City Tour - A Long Term Project - last post by @ Jul 5, 2011
"He who builds his house on sand..." - last post by @ Jul 18, 2011