Very Low Frequency (VLF) refers to radio frequencies in the range of 3 to 30 kilohertz (kHz). These frequencies are primarily used for communication with submarines and for certain types of scientific research. VLF waves can travel long distances and penetrate water, making them ideal for underwater communication. VLF signals are also utilized in geophysical studies, such as monitoring the Earth's magnetic field and studying lightning strikes. The long wavelengths associated with VLF allow them to diffract around obstacles, which enhances their ability to reach remote areas. This characteristic makes VLF valuable in various applications, including military communication and environmental monitoring.