Lipid droplets are cytosolic organelles present in nearly all cell types. Initially they were considered only as inert lipid-storage sites, but now they are recognized to be involved in other functions and even associated with liver and kidney disease. Still, the mechanisms for lipid accumulation into the lipid droplet are not totally understood. Even though the lipid and protein composition of the lipid droplets is highly dynamic, triglycerides and cholesterol esters are the main components of them. This pathway features the basic enzymatic steps necessary to esterify glycerol and cholesterol.