Yeah, a stock is basically a share in a company that you recieve when you invest money into it. When the profits of the company goes up, you recieve money for having that share. When the profits go down, you owe money.
Its a risk really.. but you can make a lot of money in it if you have an advisor or know what your doing..
Anyhow, I don't own any myself yet, but when I become a bit older (when I graduate from college), I may choose to invest in Intel and AMD.