The oscillating circuit consists of a coil and a capacitor. In addition, it may also contain a resistor (variable resistance element). An inductor (or a solenoid, as it is sometimes called) is a rod on which several layers of winding are wound, which, as a rule, is a copper wire. It is this element that creates vibrations in the oscillatory circuit. The rod in the middle is often called the choke, or core, and the coil is sometimes called the solenoid.
First, the capacitor is charged and the circuit is closed. After that, a sinusoidal electric current begins to flow in the circuit. The capacitor is discharged through the coil. In the coil, when current flows through it, an EMF of self-induction arises, directed in the direction opposite to the capacitor current
Having been discharged completely, the capacitor, due to the EMF energy of the coil, which at this moment will be maximum, will begin to charge again, but only in reverse polarity.
Oscillations that occur in the circuit are free damped oscillations. That is, without additional supply of energy, oscillations in any real oscillatory circuit will sooner or later stop, like any oscillations in nature.
This is due to the fact that the circuit consists of real materials (capacitor, coil, wires), which have such a property as electrical resistance, and energy losses in a real oscillatory circuit are inevitable. Otherwise, this simple device could become a perpetual motion machine, the existence of which, as you know, is impossible.