When you turn the ignition key, you are actually turning on the starter, which then cranks the engine. When a starter isn't working correctly, the engine may start with great difficulty, or not at all. Starter problems may be due to electrical/mechanical failure, or outright breakage.

The alternator carries out two important tasks. It recharges your battery while the vehicle is running to keep it at peak  starting power. The alternator also works with your battery as a team to operate electrical components, such as headlights, windshield wipers, and more. A malfunctioning alternator can cause electrical components  to operate erratically, or even cause your engine to suddenly stop running.

An auto radiator has a set of tubes called the "core" that the coolant flows through.
By passing through the core, the coolant is reduced to an acceptable temperature before going into the engine once again.

There has to be a place to pour in coolant and the radiator cap covers that filling hole, while also increasing the boiling point of the coolant to make it more efficient.

The coolant goes from the radiator to the engine through a series of hoses that must be sturdy and flexible enough to handle engine vibration and high heat.

Like the device on your home heating/cooling system, the engine thermostat keeps the engine at the right operating temperature.

This mechanism drives coolant through the whole cooling system, in addition to the engine block.