Firewall

Firewall may refer to:

• Firewall (computing), a technological barrier designed to prevent unauthorized or unwanted communications between computer networks or hosts
• Firewall (construction), a barrier inside a building, designed to limit the spread of fire, heat and structural collapse
• Firewall (engine), the part of a vehicle that separates the engine compartment from the rest of the vehicle
• Firewall (physics), a hypothetical phenomenon where a freely falling observer spontaneously burns up at the horizon of a black hole