An electromagnetic coil is an electrical conductor such as a wire in the shape of a , spiral or helix. Electromagnetic coils are used in electrical engineering, in applications where electric currents interact with magnetic fields, in devices such as inductors, electromagnets, transformers, and sensor coils. Either an electric current is passed through the wire of the coil to generate a magnetic field, or conversely an external time-varying magnetic field through the interior of the coil generates an EMF (voltage) in the conductor.

Coil may refer to:

• Coil (chemistry), a tube used to cool and condense steam from a distillation
• Electromagnetic coil, formed when a conductor is wound around a core or form to create an inductor or electromagnet
• Intrauterine device or coil, a contraceptive device
• Chemical oxygen iodine laser or COIL
• Coil, a binary digit or bit in some communication protocols such as Modbus
• COIL, the gene that encodes the protein coilin