STP means Straight Through Processing, which means that when you put an order in, it goes into the market and the broker buys or sells on your behalf. The alternative is where a broker matches up with other traders or does not hedge your positions at all. In the grand scheme of trading, it does not matter whether your broker is STP or uses a B-Book. You make money if you call the market right. You can’t blame the broker if your trades are not profitable. Here’s more about ECN brokers and STP brokers which may be of interest to more experienced traders