What makes a specific food “hot”?

Only two ingredients contribute to the burning sensation that “hot” foods produce: chili (of all kinds) and ginger. Chili can be fresh green chili of many varieties that we find in the grocery stores or it can be dried red chili, of either the powdered or crushed variety (the kind commonly used to sprinkle over pizza). One can put season their food with any other spice that they can find, however, if they don’t have one or both of those two ingredients in their food, a burning sensation will not occur.