# Standard electrodes

In standard electrodes, why it is necessary to maintain the pressure as 1 atmosphere, is the potential of an half cell depends on pressure too? If yes then how the potential of an half cell depends upon pressure?

Say for example, i know that in standard hydrogen electrodes we maintain the concentration and temperature as 1M and temperature 25°C since the potential depends upon temperature and concentration of the electrolyte.but why should we maintain the pressure as and1 atmosphere? If the potential depends upon pressure, how come they are related i didn't get the logic!