What is the purpose of neutralizing an amplifier?

RF amplifiers, especially those using vacuum tubes or certain transistors, can accidentally become oscillators if some of the output signal feeds back into the input in phase with the original signal. This unwanted feedback causes the amplifier to self-oscillate, which can generate spurious emissions, distort the intended signal, and even damage the equipment. Neutralization is the process of deliberately feeding a small amount of the output signal back to the input, but 180 degrees out of phase. This out-of-phase signal cancels out the internal positive feedback, stabilizing the amplifier and preventing it from generating its own continuous oscillations.