As the Earth formed and cooled, water vapor was a significant component of the atmosphere. As the planet's temperature dropped below the boiling point of water, the water vapor started to condense into liquid water droplets and eventually fell as rain. This process resulted in the formation of Earth's oceans.

The rain continued to fall until the oceans reached their current size. The presence of liquid water on Earth's surface has profound implications for life on our planet. Water is essential for all known life forms, and it has played a crucial role in shaping Earth's climate and ecosystems.