What is Coil? Connection Types

Coil is an electronic circuit element. Reacting-storing when there is an external electromagnetic effect on it; It is a passive circuit element that emits electromagnetic waves when a "f" frequency signal is applied to the terminals.
The ending is "Henri".
1 Henri = 1000 milli Henri (mH)
1 Henri = 1000,000 micro Henri (µH)
1 Henri = 1000,000,000 Nano Henri(nH)

Together with the resistor, capacitor circuit elements, they perform different functions with different connections.