What is the purpose of the unbypassed emitter resistor Re?

The unbypassed emitter resistor (Re) in a transistor amplifier circuit serves to stabilize the operating point by providing negative feedback. It improves thermal stability by counteracting variations in transistor parameters due to temperature changes. Additionally, Re enhances linearity and reduces distortion by preventing the transistor from entering saturation during operation. This resistor also plays a role in setting the gain of the amplifier, as it influences the overall input and output impedance.