I trade in Japan and it seems that there are a lot of limitations in how trades are implemented. On most stocks there are limits on how many trades you can make in one day. If you purchase once and sell, then you can make another purchase but you can't sell it off in the same day. This is really awkward if you timed something wrong, or you like to dip in and out. From what I gather these restrictions are generally absent from the US markets, giving you a lot more flexibility in how you trade. (Btw, I'm a newbie, who started in summer last year, switched to paper trading after the collapse in October (but held on to some financials I had - thankfully recovering) and restarted in April this year).