total cholesterol is the sum of all cholesterol measured in a person's blood. this total includes high-density lipoprotein (hdl), which is sometimes called the "good cholesterol," and low-density lipoprotein (ldl), sometimes called the "bad cholesterol," and very low-density lipoprotein (vldl).
cholesterol is measured either in millimoles per litre of blood (mmol/l) or in milligrams per decilitre of blood (mg/dl).
the ratio of total cholesterol to "good" (hdl) cholesterol is also important, especially if total cholesterol is high.