The chemical reactions and pathways involving lipids, compounds soluble in an organic solvent but not, or sparingly, in an aqueous solvent. Includes fatty acids; neutral fats, other fatty-acid esters, and soaps; long-chain (fatty) alcohols and waxes; sphingoids and other long-chain bases; glycolipids, phospholipids and sphingolipids; and carotenes, polyprenols, sterols, terpenes and other isoprenoids [goid 6629] [evidence IEA]; The release of triacylglycerols, any triester of glycerol, from storage within cells or tissues, making them available for metabolism [goid 6642] [evidence IEA]; The directed movement of lipids into, out of, within or between cells. Lipids are compounds soluble in an organic solvent but not, or sparingly, in an aqueous solvent [goid 6869] [evidence IEA]; The chemical reactions and pathways involving steroids, compounds with a 1,2,cyclopentanoperhydrophenanthrene nucleus [goid 8202] [evidence IEA]; The chemical reactions and pathways involving cholesterol, cholest-5-en-3 beta-ol, the principal sterol of vertebrates and the precursor of many steroids, including bile acids and steroid hormones. It is a component of the plasma membrane lipid bilayer and of plasma lipoproteins and can be found in all animal tissues [goid 8203] [evidence IEA]; The directed movement of cholesterol, cholest-5-en-3-beta-ol, into, out of, within or between cells [goid 30301] [evidence IEA]; The acquisition, loss or modification of a protein or lipid within a low-density lipoprotein particle, including the hydrolysis of triglyceride by hepatic lipase, with the subsequent loss of free fatty acid, and the transfer of cholesterol esters from LDL to a triglyceride-rich lipoprotein particle by cholesteryl ester transfer protein (CETP), with the simultaneous transfer of triglyceride to LDL [goid 34374] [pmid 15797858] [evidence IMP]; The process by which a low-density lipoprotein particle is removed from the blood via receptor-mediated endocytosis and its constituent parts degraded [goid 34383] [pmid 2563166] [evidence IMP]; The process by which a low-density lipoprotein particle is removed from the blood via receptor-mediated endocytosis and its constituent parts degraded [goid 34383] [pmid 15797858] [evidence IMP]; Any process involved in the maintenance of an internal equilibrium of cholesterol within an organism or cell [goid 42632] [pmid 2563166] [evidence IMP]; The directed movement of lipids into, out of, within or between cells. Lipids are compounds soluble in an organic solvent but not, or sparingly, in an aqueous solvent [goid 6869] [evidence IEA]