Feedback is provided by an inductance coil connected to the emitter circuit, connected to an inductor in the oscillating circuit. Oscillations in the circuit are caused in the oscillating circuit. Vibrations in the circuit cause voltage fluctuations in the coil connected to the emitter circuit. This connection provides the opening of the transistor and the flow of current through the collector into the oscillatory circuit. With a properly selected oscillation phase at the emitter junction, current from the collector circuit periodically flows into the oscillatory circuit circuit, thereby maintaining oscillations in it.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.