A metal detector is an electronic device that is designed to detect metallic objects that are hidden or buried underground or hidden within other materials. It works by using an electromagnetic field to detect changes in the conductivity of the ground or materials being scanned. The device is commonly used in a variety of industries and settings.

The usage of metal detectors includes:

1. Security: Metal detectors are commonly used in security settings such as airports, government buildings, and sporting events to detect weapons or other metallic objects that could pose a threat to public safety.
2. Archaeology: Metal detectors are used in archaeological settings to locate buried artifacts and other historical objects. They are often used in conjunction with excavation tools to carefully uncover buried objects without damaging them.
3. Construction: Metal detectors are used in construction settings to locate buried pipes, cables, and other utilities that may be hidden underground. This can help prevent damage to these utilities during construction activities.
4. Mining: Metal detectors are used in mining operations to detect metal ore deposits and to locate other valuable minerals. They are also used to detect metal objects that may be present in the ore or other materials being mined.
5. Recreational Activities: Metal detectors are used by hobbyists and treasure hunters to search for buried objects such as coins, jewelry, and other artifacts.

Overall, metal detectors are useful devices that are used in a wide range of industries and settings. They are designed to detect metallic objects that may be hidden or buried, and they have many applications, from security and archaeology to construction and mining.