Rainfall is the process by which water droplets fall from the atmosphere to the Earth's surface. It occurs when clouds become saturated with moisture, leading to the condensation of water vapor. This process is essential for replenishing freshwater sources, supporting plant growth, and maintaining ecosystems. Rainfall is measured in millimeters or inches and can vary greatly depending on the region and season. Areas with high rainfall, such as rainforests, receive significant amounts of precipitation, while deserts experience very little. Understanding rainfall patterns is crucial for agriculture, water management, and predicting weather events.