The plat for your community is an important governing document. The plat is an aerial depiction of the lot boundaries, roadways, common areas, and easements. The filing of the plat and declaration is what creates the community. The plat contains a metes-and-bounds description of the development and the dimensions of each lot and unit. Plat maps can contain very important information. For example, it may show easements, utility line locations, and maintenance obligations--all of which may or may not be found in the CC&Rs or Declaration.
For planned communities, the plat also identifies the common areas. Sometimes, common areas are referred to as "Tracts". Here's an example of a plat depicting a common area, owned by the association:
Condominium and planned community plats are slightly different in the type of information which must be contained in the plat. For condominiums, plats must show the elevations of the units. For example:
If you do not have a copy of the plat for your community, you can get a copy from your county recorder or survey department. Here are the links to locate and download plat maps: