Why do prices for common goods and services fluctuate over time?

Prices for common goods and services go up and down over time like the waves at the beach.

Imagine you're trying to buy your favorite toy. One day, it costs $5, but a few weeks later, it goes up to $7. Then, after a while, it drops back to $5 again. This happens because supply and demand are playing a game together.

If lots of kids suddenly want the same toy, like during a big holiday, stores might not have enough toys to go around. That means demand is high, so stores can charge more money for each toy, just like when you want something really badly and are willing to pay extra for it.

On the other hand, if the store gets a big shipment of that same toy, there are more toys to go around. Now supply is high, so stores might lower the price to sell more toys, just like when you have a lot of candy and want to share it with your friends.

Sometimes prices even change because things get more or less expensive to make, like if the paper used for wrapping gifts gets more expensive, that can affect how much stores charge for the toy inside.