The wet method for caramel involves adding water to the sugar before cooking. When stirred well, the water coats each crystal and ensures they do not crystalize again as they melt and caramelize. It's very important to stir the sugar and water together very well! If any amount of dry sugar is left on the sides of the pan and it comes in contact with melted sugar, the dry crystals will communicate with the melted ones and tell them to re-crystalize.