Cholesterol has multiple effects on lipid bilayers. Cholesterol (a) changes the fluidity (b), thickness (c), compressibility (d), water penetration (e), and intrinsic curvature (f) of lipid bilayers. Cholesterol also induces phase separations in multicomponent lipid mixtures (g), partitions selectively between different coexisting lipid phases (h), and causes integral membrane proteins to respond by changing conformation (i) or redistribution (j) in the membrane.