Buying stock in a company is, basically, buying a very small piece of that company.  When a company wants to raise money, they issue stock...  They sell little pieces of the company.  You become a stockholder in that company and get the opportunity to go to yearly meetings and vote on who's on the company's board of directors and any big changes in the rule's of how the company runs.  Most people don't actually go to these meetings since they are often in another part of the country (or in another country), but you can still send in your vote.

Investing in stocks is not like putting your money in the bank...  where it's safe and where you get a pretty set (but low) interest rate.  If the company does well, you do well.  If the company stinks, you stink.  In fact, you can lose all your money!  If you put $10,000 in the bank, you won't make much money in interest, but your $10,000 will always be there and it will be safe.  If you invest $10,000 in a stock, you COULD make 70% return (increase) on your money...  Or you could lose it all and end up with zippo... ziltch...  nada! 

That's the deal.  If you want to make more than 1% in interest (or whatever pathetically low amount savings accounts are paying these days), you have to take the risk.  Some stocks are riskier than others -- like stock in a brand new company...  Who knows what will happen there.  Some stocks are safer than others -- like stock in a really old, stable company that makes a product or service that everyone uses.