system
Given the following post, respond as if you're commenting on Reddit:
human
Can someone explain to me how the stock market works? (LI5)

I have a decent general knowledge but economics is my big weak point. I'd really like to learn more. What forces cause the stock market to move up or down?
gpt
Your lemonade stand decides to go public, so you take its worth, divide it into a certain amount of stocks and then start selling them to people. (1 billion, 1 billion stocks so 1 stock = $1). 

When you do well people want your stocks, so they buy them, but people that already own it want more money, so they sell for higher then $1, stock price goes up. Reverse happens when you do badly, people don't like your company so they sell, market gets flooded and stock goes down.