Have you ever watched a balloon rise high in the air and then slowly come back down a bit? Prices of things like stocks and cryptocurrencies can do that too. The Fibonacci retracement method is like a fancy tool that uses some special numbers to try and predict where those prices might stop and "retrace" (come back down a bit) before going up again. It's not a guaranteed way to know the future, but it can be helpful for some investors.
