Media market

[1] They can coincide with or overlap with one or more metropolitan areas, though rural regions with few significant population centers can also be designated as markets.

However, geography and the fact that some metropolitan areas have large cities separated by some distance can make markets have unusual shapes and result in two, three, or more names being used to identify a single region (such as Wichita–Hutchinson, Kansas; Chico–Redding, California; Albany–Schenectady–Troy, New York; and Harrisburg–Lebanon–Lancaster–York, Pennsylvania).

Market researchers also subdivide ratings demographically between different age groups, genders, and ethnic backgrounds, as well as psychographically between income levels and other non-physical factors.

The TMAs not only have full control over local broadcasts, but also delineate which channels will be received by satellite or cable subscribers ("must-carry" rules).

A similar term used by Nielsen Media Research is the Designated Market Area (DMA), and they control the trademark on it.

DMAs are used by Nielsen Media Research to identify TV stations that best reach an area and attract the most viewers.

In 2009, Nielsen began offering radio ratings in competition with Arbitron, starting in those markets ranked 101st and smaller.