I'm water! It's hard to see me because I am surrounded by a lot of other water! I'm currently in the ocean, but I'm about to evaporate.
I'm now water vapor. I have evaporated (turned in a gas from a liquid). Later, I condense and turn from a gas to a liquid. Once again, I am a water droplet.
As the more and more droplets form, the water becomes too heavy to remain in the air. Precipitation then occurs - water descends from the atmosphere in a solid or liquid form. This is usually in the form of rain, sleet, snow, or hail.
Now that I've reached the ground, I might become runoff. I flow on the surface of the ground without actually going beneath the surface. For example, I might end up in a river.
Or, I might take part in the infiltration process. I soak into the ground (and become groundwater), eventually flowing towards the ocean.
Whether it's runoff or infiltration, I always end back up in the ocean for the process to start all over again. Again and again, until the end of time it seems...