Hi. Amateur question here. I've been 'messing around' with stocks abit, using TradeKing. Recently I had the chance to see Interactive Brokers in action and the question is this: In TK, when you buy a stock, say GOOG, you simply... click buy. In IB, you can choose the exchange. Example: GOOG Stock SMART USD NMS GOOG Stock ARCA USD NMS and so on. What is the difference? What is going on that I cannot see in TK? Pardon the ignorance, Dane