Diffusers are used to help protect your tagine from damage from the heat whilst cooking on your hob. They are also used for reducing the heat to the lowest possible level giving an even temperature over the base of your pot. Using a tagine diffuser helps prevent food from burning, sticking and boiling dry.
Difusers are designed to be used on both gas and electric hobs. If you have an induction heat source then Emile Henry have produced their induction disc product for use with their Flame products/tagines.