A sector is a continuous and commonly recognized market area which is not necessarily dependent on any official boundaries, and which is not exclusively defined. Sectors can overlap each other and any other boundaries.

Like a zone, a sector is often not officially defined, and its boundaries may be interpreted based on common usage or market situations. Their extent follows the recognized market area, including where it crosses city boundaries.

The market relationship and common recognition define the area. A municipal line or a single development boundary need not delimit that market, and different market sectors can cover some of the same ground.