What is standard hydrogen electrode ?

A standard hydrogen electrode (SHE) is a reference electrode used to measure the electrode potential of other electrodes. It consists of a platinum electrode in contact with 1M hydrogen ion solution and hydrogen gas at 1 atm pressure at 25°C. 

The platinum helps in the transfer of electrons and acts as an inert surface. The potential of SHE is defined as 0 volts, and it serves as a baseline for comparing the reduction potential of other electrodes.