Many developers divide a large tract of land into lots as a subdivision. Certain areas of the land are dedicated (given to local government for permanent upkeep) as streets and sometimes alleys for transport and access to lots. Areas between the streets are divided up into lots to be sold to future owners. The layout of the lots is mapped on a plat diagram, which is recorded with the government, typically the county recorder's office. The blocks between streets and the individual lots in each block are given an identifier, usually a number or letter.