A snubber circuit is used to absorb spike noise and includes a resistor and capacitor connected in series.
Spike noise is generated by the back electromotive force that occurs due to the circuit's inductance when the current changes. When a magnetic field is generated by a current in accordance with the right screw rule (Ampere's rule) and a magnetic flux change then occurs due to a change in the current, the following type of voltage is generated by the resulting back electromotive force.
dV = -dΦ/dt (Φ: Magnetic flux)
This is the reason a light bulb often blows when the light is turned out.
Because spike noise often occurs when the power supply of the induced load is switched on and off, this noise can be absorbed by connecting a snubber circuit to the switch or relay.