Alternator - recharges the battery to replace the electricity used to start the car, and to run the accessories and electrical system. Air Cleaner - Houses the air filter which filters the air going into the engine to be mixed with fuel. Inspect when you change your oil, change if it's dirty. Brake Power Booster - Often just called the brake booster. Brake Master Cylinder - Brake pedal pushes piston inside of this to provide pressure at wheels to stop the car.
Brake fluid is checked here.
As coolant expands, some is pushed into this tank, drawn back into radiator as engine cools. Provides large surface area for air to remove the heat by convection. Under pressure when hot, must have a good cap to maintain pressure. Heater Motor - Often called the blower motor. This is what makes the air come out of the heater when it's cold and your air conditioner when it's hot.