NDBs, or Non-Directional Beacons, are radio navigation aids used in aviation and maritime navigation. They emit signals in all directions, allowing pilots and mariners to determine their position relative to the beacon. NDBs operate on low to medium frequency bands, making them effective for long-range navigation. These beacons are often used in conjunction with other navigation systems, such as VORs (VHF Omnidirectional Range) and GPS (Global Positioning System). While NDBs are less common today due to advancements in technology, they still play a role in providing reliable navigation information, especially in remote areas.