Final answer:
A protective hood, often made from a material like Nomex, provides critical protection for a firefighter's head, shielding it from the intense heat of fires.
Step-by-step explanation:
A protective hood, such as a Nomex hood, is an essential piece of personal protective equipment commonly used by both racers and firefighters. It is designed to be worn on the head and over a firefighter's face mask during hazardous conditions. The primary function of the hood is to offer additional protection to the parts of the head that are not covered by other gear like the helmet and face mask, especially from the high temperatures and potential burns associated with fires.