What is the job of the coolant and what substance is most commonly used?

The job of the coolant is to absorb and dissipate heat from an engine or system to prevent overheating, ensuring optimal performance and longevity. The most commonly used coolant is a mixture of water and antifreeze, typically ethylene glycol or propylene glycol, which lowers the freezing point and raises the boiling point of the fluid. This mixture helps maintain a stable operating temperature across a range of conditions.