Well, what we basically do when we add our detergent into our liquid is we replace the surface water molecules with our detergent molecules. So this is the arrangement that we basically have. So what happens is, on the surface, instead of having the water molecules, we now have our detergent molecules. And these hydrophilic polar heads shown in blue will orient and interact with the water molecules. But the hydrophobic tails, the non polar green tails will basically orient away from the water molecules and to the air. So we essentially replace our water molecules on the surface with these hydrophobic hydrophilic detergent molecules.