Coils are classified according to inductance

Classified by inductance form: fixed inductance, variable inductance.
Classified by the properties of the conductive magnet: hollow core coil, ferrite coil, iron core coil, copper core coil.
Classified by job nature: antenna coil, oscillation coil, choke coil, notch coil, deflection coil.
Classified by winding structure: single-layer coil, multi-layer coil, honeycomb coil.