Very Low Frequency (VLF) refers to a range of radio frequencies from 3 kHz to 30 kHz. These frequencies are used for various applications, including communication with submarines and navigation systems. VLF waves can travel long distances and penetrate deep into the ocean, making them ideal for military and maritime communication. VLF signals are also utilized in scientific research, such as studying the Earth's ionosphere and monitoring natural phenomena like lightning and geomagnetic storms. Due to their low frequency, VLF waves can diffract around obstacles, allowing them to be received even in challenging environments.