So phospholipids can be described by using this pictorial image. We have this head, this spherical region that describes the phosphate as well as the choline, if we have that choline. So this is the polar region of our phospholipid. So the left side is the polar hydrophilic region, the right side is the non polar hydrophobic region. So these two fatty acids that are described by using these tails, so two tails describe the two fatty acids and they're connected via the glycerol to the polar phosphate group. Now the question is, how exactly do the phospholipids arrange themselves inside the cell membrane to actually give our cell membrane its structure, the bilayer structure?