Explain why cell surface membranes are also called 'phospholipid bilayers'?

A cell surface membrane is made up of a type of molecules called phospholipids, so what is a phospholipid bilayer? The first step would be to break down the term. ‘Phospho’ means that the molecule(s) must contain a phosphate group; ‘lipid’ is any compound made up of fatty acids; and ‘bilayer’, means two layers. So a cell membrane must contain phosphates + lipids + two layers; in other words, molecules made up of a phosphate and a lipid somehow form two layers to make a cell membrane. How? There is a very simple trick that phospholipids use to create a cell membrane, and it all comes down to their structure. The Phosphate groups of the molecules are hydrophilic (water loving), whilst the lipid part is hydrophobic (water hating). The molecules therefore arrange themselves so their water loving phosphate ‘heads’ point towards the water (or cell medium), and the water hating tails point away. Because these phospholipids will be surrounded by watery material inside and outside the cell, they arrange themselves so there are two layers, but with their ‘heads’ pointing outwards and their ‘tails’ pointing inwards towards each other.
So if we were to answer the above question in an exam, it must make reference to the hydrophilic (phosphate) parts associating with water, the hydrophobic (lipid) parts being repelled from water, and they bilayer forming by the hydrophobic parts pointing towards each other.