Desalination involves removing salt from seawater. There are many ways that we can separate salt from water. One way is called distillation - the process of heating up water so that it changes into a gas, and it leaves any little solid particles behind, including salt. Once the water cools down, it turns back into a liquid, but now it is pure and fresh. Another way to desalinate water is called reverse osmosis. In reverse osmosis, salt water is forcefully pushed through a wall-like barrier that has many tiny holes in it. These holes allow the water to pass through, but they do not allow the tiny salt particles in the water to pass through. It acts like a very powerful filter, separating the salt and water.