Public service and traffic nets are part of a tradition that dates back almost to the dawn of Amateur Radio. The ARRL, in fact, was formed to coordinate and promote the formation of traffic nets. In those early days, nets were needed to communicate over distances longer than a few miles. Public service and traffic nets benefit hams and nonhams alike. Many missionaries in South America, keep in touch with stateside families and sponsors via Amateur Radio.
Most nets are local or regional.
They use many modes from slow-speed CW nets in the Novice HF bands, to FM repeater nets on 2 meters. This has obvious advantages for amateurs sending traffic over long distances, as VHF FM nets usually cover only a local area. NTS includes four different net levels which operate in an orderly time sequence to effect a definite flow pattern for traffic from origin to destination. A message flows through the NTS in a manner similar to an airline passenger who starts out in a small residential town with a destination across the continent in another small town. He has to change carriers many times in the process, starting with a local ground conveyance to a feeder airline, to a transcontinental airline, to another feeder airline then local transportation to deliver him to his destination.