What is a power diode and how does it differ from signal diodes?

Power diodes are two-terminal semiconductor devices that conduct current in one direction (forward-biased) and block in reverse. Unlike signal diodes, power diodes handle high currents (tens to thousands of amperes) and high voltages (hundreds to thousands of volts). They have larger junction areas, require heat sinking, and have longer reverse recovery times. Key parameters include forward voltage drop (0.7-1.5V), reverse recovery time, and thermal resistance.