What is it? What is the working principle of semiconductor switch? Help!

A semiconductor switch is an electronic switch that uses the on and off characteristics of semiconductor devices, such as transistors and silicon controlled rectifier, to turn on and off the circuit. Its characteristic is that it does not generate sparks when switching on and off the circuit, because the semiconductor device itself has leakage current and mosfet, and its disadvantage is that it cannot completely switch on and off the circuit when switching on and off the circuit.