A stock split is essentially when a company increases the number of shares. For example, if you owned 25 shares of XYZ at $15 per share, and there was a 2-1 stock split, you would then own 50 shares worth $7.50 each. Why do companies issue splits if you still have the same amount of money?
Liquidity. Some companies believe that their stock should be inexpensive so more people can buy it. This creates a condition where more of the company's stock is bought and sold [this is called "increased liquidity"]. The problem, in theory, is that the increased activity will also leads to bigger gains and drops in the stock, making it more volatile.
Many investors believe splits are a good thing. (Their thinking goes "Well, if the stock was at $15, and now it's at $7.50, it has to go back up to where it was!) This is wrong.
