Lipoproteins are biochemical assemblies containing both proteins and lipids that transport fats like triglycerides through the water-based plasma. They consist of a nonpolar lipid core surrounded by a layer of amphipathic lipids and proteins. Lipoproteins can be classified based on density, electrophoretic mobility, and apolipoprotein content. They transport lipids between tissues and are involved in lipid metabolism through interactions with enzymes like lipoprotein lipase. Defects in lipoprotein metabolism can cause diseases like atherosclerosis and coronary artery disease.