Real estate refers to land and improvements that are physically attached, as well as rights to own or use them. Real estate includes the land itself from the surface to the center of the earth, as well as anything permanently affixed (improvements), attached objects that have become part of the property (fixtures), and associated rights or privileges (appurtenances). Land can be described through metes and bounds surveys, the rectangular survey system of townships and sections, or reference to recorded plats and maps. Real estate has physical characteristics like immobility and indestructibility, as well as economic characteristics like scarcity and fixity.