Shortwave radio is radio transmission using shortwave frequencies, generally 1.6–30 MHz (187.4–10.0 m).
Shortwave radio has an ability to enter a state of skywave or skip propagation, in which the radio waves are reflected or refracted back to Earth from the ionosphere, as opposed to being absorbed. it allows the transmitted signal to be reflected around the curve of the Earth, thus shortwave is not line-of-sight. This allows for very long distance communications. Shortwave radio is used for broadcasting of voice and music to shortwave listeners over very large areas; sometimes entire continents or beyond. Additionally, it is used for two-way international communication.