So whenever a lipid contains fatty acids, it's the fatty acid component of the lipid that makes it hydrophobic nonpolar. That basically gives it the ability to remain insoluble in an aqueous environment. So, because fatty acids are so dominant and so important, in this lecture, I'd like to focus on what fatty acids actually are, the systematic approach to naming fatty acids, and then discuss some properties of fatty acids and how going from one fatty acid to another fatty acid, the properties may actually change. So what exactly are fatty acids? Well, fatty acids are molecules that contain a hydrocarbon chain, and at the end of that hydrocarbon chain, we have a carboxylic acid. So, two types of groups in a fatty acid, the hydrocarbon chain, which is nonpolar, and the carboxylic acid, which is actually polar.