So now the hand acts as the impermeable barrier. What will happen next? Well, as the water tries to move across this barrier, because we have an impermeable barrier, our hand, the water, will not be able to move across. And that's because our hand, the impermeable barrier, actually creates a pressure that prevents that osmosis from taking place. And that's exactly what osmotic pressure is. Osmotic pressure is the pressure that needs to be applied to actually prevent osmosis from actually taking place.