The stock market, like any market, is where things are bought and sold.
In this case, the things for sale are companies themselves.
Most big businesses around the world are worth a huge amount of money, so they are divided up so people can buy a share of the company.
These are called, funnily enough, shares.
When people are feeling good about a company – maybe because it is selling a lot more games consoles than last year – more people want to buy shares in it.
That means that the price goes up, as people are willing to pay more for a share of a successful company.
And the opposite is true. If people are feeling bad about a company – maybe the new console it’s selling is poor quality – then the share price goes down.
