I've just read something about day trading. As Mr. Wiki says, refers to the practice of buying and selling financial instruments within the same trading day such that all positions are usually closed before the market close for the trading day.
I think this has to be one of the most 'exciting' jobs as one has to be gifted in somehow taking 'chances' in the trade. One can either experience profit or loss. If one is a high risk day trader, so he or she may experience extreme profit or extreme loss. So, I guess this job is not for the faint hearted like me. :)