Why FEt is source follower?

A Field Effect Transistor (FET) operates as a source follower due to its configuration where the output is taken from the source terminal. In this setup, the input signal is applied to the gate, and the output voltage at the source closely follows the gate voltage, minus a small threshold voltage drop. This characteristic allows the source follower to provide a high input impedance and low output impedance, making it an effective buffer for signal amplification without significant gain.