What Makes a Planet 'Habitable' for Life?

Imagine a planet where it's too hot, like a summer day in the desert, no water can stay liquid. Or too cold, like the North Pole in winter, water freezes and stays solid forever. A habitable planet is one that has just the right temperature for water to be liquid, because life as we know it needs water to grow and thrive. It also helps if the planet gets light from a star, not too bright or too dim. Scientists call this the Goldilocks Zone, like Goldilocks who tried out different porridges, one was too hot, one too cold, but just right in the middle.