Citizens' Band radio (CB) is, in most countries, a system of short-distance,
simplex radio communications between individuals on a selection of 40 channels within the 27
MHz (11 meter) band. The CB radio service should not be confused with
FRS,
GMRS,
MURS, or
amateur ("ham") radio. Similar personal radio services exist in other countries, with varying requirements for licensing and differing technical standards. In many countries, CB does not require a license and, unlike amateur radio, it may be used for commercial communication.
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