Why Do Inflation and Interest Rates Often Move Together?

Imagine you're selling lemonade. If the price of lemons goes up, your lemonade costs more, that's like inflation. Now imagine you borrow money from a friend to buy lemons. Your friend says, 'I'm going to charge you a little more for borrowing my money because prices are going up.' That extra cost is like an interest rate. When prices go up (inflation), people often raise the price of borrowed money (interest rates) too.