Non-Directional Beacons (NDBs) are radio transmitters that emit signals in all directions. They help pilots and mariners navigate by providing a reference point for their location. NDBs operate on low-frequency radio waves, allowing them to be received over long distances, even in poor weather conditions. NDBs are often used in conjunction with other navigation aids, such as VORs and GPS, to enhance accuracy. Pilots can tune their aircraft's radio equipment to the frequency of an NDB to determine their bearing relative to the beacon. This information is crucial for safe navigation, especially in areas without visual landmarks.