Shortwave refers to a portion of the radio frequency spectrum that typically ranges from 3 to 30 megahertz (MHz). It is used for long-distance communication because shortwave signals can bounce off the ionosphere, allowing them to travel beyond the horizon. This makes it popular for international broadcasting and amateur radio. Shortwave radio is often used by broadcasting organizations to reach audiences in different countries, especially in remote areas. Additionally, it is utilized by hobbyists and emergency services for reliable communication during disasters when other systems may fail.