Phospholipids are found in the cell membranes of organisms, where they form the lipid bilayer surrounding the cell. They also make up most of the structure of biological membranes in general.
Phospholipids are fat derivatives consisting of a lipid with one or more phosphate groups attached to it. The phosphate group replaces one fatty acid group. Phospholipids are amphipathic compounds, meaning that the head is hydrophilic and the tail is hydrophobic. The first phospholipid identified, lecithin, was discovered in egg yolks by Theodore Nicolas Gobley in 1847. Purified phospholipids have been produced commercially and are regularly used in nanotechnology and materials science.