1) Heat transfer from fins can be characterized by fin effectiveness, which is defined as the ratio of actual heat transfer from the fin to the maximum possible heat transfer if the fin was made of an ideal material with infinite thermal conductivity. 2) Fin efficiency is defined as the ratio of actual heat transfer from the fin to the heat transfer if the fin was at the same temperature as the base. 3) Overall fin efficiency takes into account an array of fins and is defined as the ratio of total heat transfer from the fin array to the heat transfer without fins. Enhancing overall fin efficiency involves increasing the total surface area including the fin area.