A brew head is the top part of a brewing vessel where hot water and beer meet. It is also known as a kettles lid, false bottom, or steam jacket. The purpose of the brew head is to hold in heat and prevent liquid from boiling out of the kettle. There are two types of brew heads: direct fire and indirect fire. Direct fire brew heads have a heating element that goes around the outside of the kettle. Indirect fire brew heads have a heating element that goes underneath the kettle. The most important thing to remember when choosing a brew head is to make sure that it fits your kettle correctly. If it is too small, heat will escape and your beer will not boil properly.