Minecraft wiki entry for Time-saving_tips, associated text: Pressure plates are handy for automatically closing doors and gates behind you without you having to stop, turn around, and close them manually. You should generally place them on only the 'safe' side of a door or gate, particularly when mining. Word of warning: If you have tamed wolves or ocelots walking around your house, they may step on the pressure plate and open the door, letting hostile mobs walk in. They also then serve to orient you towards the exit or towards unexplored areas, which makes getting into and out of the mine significantly quicker. As a bonus, if you hear a pressure plate trigger, you are warned there's a mob somewhere nearby in a supposedly safe area.