What Causes the ‘Hum’ in a Refrigerator?

Your refrigerator makes a hum because it uses something called a compressor, which is like the heart of your fridge. Every time it starts working, it vibrates and creates that low sound you hear. It's kind of like when you press your hands together to make a soft thump, that’s vibration too! The hum happens all day long because the compressor keeps turning on and off to keep your food cool.