Satellite radio uses signals broadcast from satellites to provide digital radio services over wide geographical areas, unlike terrestrial radio which has limited range. The document discusses two main satellite radio providers in the US - SiriusXM, formed by the 2008 merger of Sirius and XM, and Worldspace which operated services in other parts of the world. It compares features of satellite radio like monthly fees and channel offerings to AM/FM radio. Howard Stern is noted as a prominent radio host who moved to Sirius due to fewer content restrictions.