Stock market bubble

A stock market bubble is like when a lot of people start to buy a certain type of stock because they think it will become more valuable. This makes the stock more expensive and its value goes up faster than usual. Eventually, people might realize that the stock is too expensive and they stop buying it. When this happens, the stock's value goes way down and it is called a "bursting bubble". It is called a "bubble" because it inflates quickly then deflates just as fast.