FRS (Family Radio Service) is a walkie talkie system used in the United States. These radios use narrow band FM modulation over low power to communicate half-duplex over short distances. The maximum power allowed is .5 Watts. That is not a lot of power. Reach depends on the presence of obstacles such as trees and buildings. One can expect to maintain communications over a distance of a few hundred meters, to over a kilometer, depending on terrain.
These radios operate in the UHF (300 MhZ to 3 GhZ) band over 14 channels. The first 7 channels are shared with another, much more powerful system, called GMRS (General Mobile Radio Service). The FRS channels themselves start at 467.5625 MhZ and go up to 467.7125 MhZ. The spacing between the channels is 12.5 kilohertz. The channels shared with GMRS start at 462.5625 and go up to 462.7125.
Users do not need a license to use a FRS radio.