Rainfall is the amount of rain that falls in a particular place over a specific period of time. When meteorologists measure rainfall, they're tracking how many inches or centimeters of water have fallen from the sky, usually using a rain gauge (a simple cylinder that collects and measures precipitation).

Different places get vastly different amounts of rainfall. A desert might receive only a few inches per year, while a tropical rainforest can get over 100 inches annually. Farmers pay close attention to rainfall because their crops need the right amount: too little and plants wither, too much and fields flood.

The word can describe a single storm's downpour or patterns over months and years. When someone says “We've had heavy rainfall this spring,” they're talking about the total amount that's fallen, not just one rainy day. Scientists study rainfall patterns to understand climate, predict droughts, and help communities plan their water supply. Ancient civilizations often settled near rivers with predictable rainfall, while modern cities sometimes struggle when rainfall patterns shift unexpectedly.