Here are some links for you to start with. I hope this helps <a href="http://www.investopedia.com/articles/trading/06/Level2Quotes.asp" rel="nofollow" target="_blank">http://www.investopedia.com/articles/trading/06/Level2Quotes.asp</a> If you have any questions,i don't know everything, but i am a WHIZ at L2 :) happy trading.