A compost bin is the container used to make compost. Commercially these bins may be made of hard plastic, and is commonly cylindrical in shape, although a variety of shapes and sizes are available. The manufactured bins are commonly found in urban and suburban areas, and in some districts of North America and the U.K., local authorities subsidise the cost to encourage public waste stream reduction. They also may be user-made out of wood, or whatever salvaged, recycled materials are at hand, particularly in rural areas or where larger amounts of yard and garden waste are generated. In some areas, community bin sites are provided. Compost bins can be as simple as a square slatted wood enclosure or as sophisticated as a tumbler, which allows for the “pile” to be turned for aeration purposes.