How are phospholipids arranged in a plasma membrane?

Phospholipids are made up of a phosphate group head and two fatty acid tails. A glycerol molecule connects the two components. The phosphate group head is hydrophilic or water-loving, while the two fatty acid tails are hydrophobic or water-hating. 

The plasma membrane is made up of a double layer known as the lipid bilayer. In the outer layer of the plasma membrane, phospholipids are arranged in such a way that they line up next to each other with their hydrophilic heads facing the outside of the cell and their hydrophobic tails facing inside the cell. In the inner layer, the phospholipids are arranged with the heads facing the inside of the cell and the tails facing away from the cell. Both layers together form the bilayer plasma membrane.