There are 13 basic heat removal methods to cool IT equipment and to transport unwanted heat to the outdoor environment. This paper describes these fundamental cooling technologies using basic terms and diagrams. 11 of these methods rely on the refrigeration cycle as the primary means of cooling. Pumped refrigerant systems provide isolation between the primary heat removal system and IT equipment. The direct air and indirect air methods rely on the outdoor conditions as the primary means cooling making them more efficient for mild climates. The information in this paper allows IT professionals to be more involved in the specification of precision cooling solutions that better align with IT objectives.