The main classes of lipids are fats, lecithins, cephalins, waxes, and sphingomyelins. Their main property is non-polarity such that they avoid water. Membranes are high in lipids, and this is important to the permeation of various substances through the membranes.
Waxes coat the structures of living materials.
The sketch shows a fatty acid. Almost all have an even number of carbon atoms. The one shown is much less common than those that have 16 or 18 carbon atoms. Note the long chain of non-polar organic groups terminated by a carboxyl group shown in red. Click if you don't know the notation for carboxyl groups .