Water changes states when temperatures fluctuate. So when the air cools enough, water vapor has to condense on particles in the air to form clouds. This process is very noticeable on plants as they dew in the morning. As clouds form, winds move them across the globe, spreading out the water vapor. When eventually the clouds can't hold the moisture, they release it in the form of precipitation, which can be snow, rain, hail, etc.
Infiltration occurs when precipitation seeps into the ground.
This depends a lot on the permeability of the ground. Permeability is the measure of how easily something flows through a substance. The more permeable, the more precipitation seeps into the ground. If precipitation occurs faster than it can infiltrate the ground, it becomes runoff . Runoff remains on the surface and flows into streams, rivers, and eventually large bodies such as lakes or the ocean.