Now, although we have many different types of lipids that exist in nature, the lipids that we're going to focus on are the lipids that will find in the cell membranes of eukaryotic cells as well as bacterial cells. And there are three lipids that will find in cell membranes. So we'll find phospholipids glycolipids as well as cholesterol molecules. Now, in this lecture, we're going to focus only on phospholipids. So there are two types of phospholipids. We have phosphoglycerides and we also have spingolipids.