Metal detectors are devices used to find metal objects buried underground or hidden in other materials. They work by generating an electromagnetic field and detecting changes in that field caused by metal objects. Commonly used in treasure hunting, construction, and security, metal detectors can locate items like coins, jewelry, and even larger objects like pipes. There are different types of metal detectors, including VLF (Very Low Frequency) and PI (Pulse Induction) models, each suited for specific tasks. Many hobbyists enjoy using metal detectors on beaches or historical sites, while professionals may use them for archaeological digs or to locate landmines.