A diode is a semiconductor electronic element made mainly of silicon, which is equipped with two terminals - positive and negative, and its main task is to conduct electric current. The specific thing about diodes as elements is that they conduct electric current in a p-n transition, that is, positive to negative charged particles. The positive electrode is called the anode and the negative electrode the cathode. When switched on in the forward direction, the resistance of the diode is small and the electric current flows, but when switched on in the opposite direction, the resistance is too high and no current flows.
Protection diodes also called Transil are a type of diodes that protect sensitive electronic components as well as semiconductors from reverse voltage peaks. Unlike other types of diodes, they are more sensitive and some models also work bi-directionally, that is, they protect electronic devices from negative voltage as well. They are mainly used in electronics in radio and television.
Their name comes from the purpose that they protect, and Transil comes from transient-voltage-suppression, which means a device for suppressing transient voltage. They are also called Suppressor. In particular, depending on the application, bidirectional protection diodes can be combined at both ends with unidirectional ones.