What is a simple subject?

Let's talk about rain.

Rain is water that falls from the atmosphere to the Earth's surface. It's formed when water vapor in the air condenses, forming clouds. When these clouds become saturated with water droplets or ice crystals, they become heavy enough to fall as precipitation. Rain is essential for life on Earth, providing water for plants, animals, and humans. Different types of rain exist, including drizzle (very light rain), showers (brief bursts of rain), and thunderstorms (rain accompanied by lightning and thunder). The amount of rain an area receives can vary greatly depending on its location and climate.