Sand is the well known gritty taste found in the mouth after eating sausages at a beach barbecue. It comes in many different colours, most of them yellow, and is used for lying on, making castles out of, and for making sausages get that gritty barbecue taste.
Sand is also very important to beach life, as it is much softer on bare feet than, say, stones - (which are not often yellow and taste more crunchy than gritty in sausages, as well as being harder to swallow) and it is very relaxing. Not all sand is yellow, some of it is black, and in some places, such as Alum Bay on the Isle of Wight, you even get multi-coloured sand, which is used to make sand pictures.
Sand is made by big rocks being ground into smaller rocks, and these rocks are then ground into small stones, and then pebbles, and finally sand. Rumours that say that if sand was ground it would turn into ground coffee are all, sadly, false. Most sand is ground by the sea, although it can also be ground by wind, other stones etc. Sand is not unique to our planet, but also exists on many other moons and planets in our solar-system. In fact, sand's most famous film role (apart from being one of the great attractions of the TV series "Baywatch") was appearing as the Moon in Kubrick's "2001: A Space Odyssey", in which it was painted so it would look exactly like the sand on the moon.
All sorts of creatures live in sand, many of them are types of fish, and many more are ostriches. In the desert, a whole range of creatures live in sand. A final note about sand is that it can often be found at deserts, and is unique in being the only thing except camels which actually enjoys desert life.