5) Users "opt-in" to placing their orders in a Dark Pool. The users are intelligent traders who understand the advantages of not displaying their orders at an exchange.
6) Dark Pool trades are bound by the "NBBO" or National Best Bid and Offer. Prices cannot be chosen arbitrarily, many times the price is actually the midpoint of the NBBO but a stock cannot trade outside the NBBO without an inter-market sweep satisfying orders on other markets.
7) More volume is trading in the Dark Pools because it works for institutions. The percentage of non-exchange trades has grown to roughly 33 percent of all trades up from 8-10 percent a decade ago; this is because the users of Dark Pools have had a better experience in the dark than at an exchange.
(Read More: Man Vs. Machine: The New Kings Of Wall Street)
8) Different Dark Pools have different features to appeal to different segments of the market. Some only allow certain types of traders, say "Buy Side to Buy Side" so naturals can trade with each other. Other Dark Pools allow you to rank your contra trading partners and opt out of those you don't want to trade with. This allows the traders to create a customized experience different than the exchange one size fits all approach.
9) Orders in dark pools are like ice bergs. For a trade to take place, a resting bid, or buyer, has to be present when a seller initiates a sale. Many times both sides are not present at the same moment as orders are cancelled and replaced, these orders are referred to as "ships passing in the night".
10) The biggest reason people are afraid of "Dark Pools" is the name, like a kid being stuck in a closet by a mean sibling, the image is frightening. Maybe they should be called "Block Trading Venue for Institutional Traders Who Know What They are Doing". BTVITWKWTD -Doesn't exactly roll off the tongue does it?
Now trying to understand how Dark Pools interact with high frequency trading is a whole other conversation. One that needs more than a top 10 list, and I think better for another time.
(Watch: For a good look at all the questions and concerns surrounding dark pools, check Wall Street Journal reporter Scott Patterson's CNBC interview about his book called "Dark Pools.")
D. Keith Ross is the Chief Executive Officer of PDQ Enterprises, owner of PDQ ATS, a new equity trading venue that emulates the interaction and dynamism of traditional floor brokers in a high-speed, electronic trading environment, where algorithms compete to fill orders. Prior to PDQ, Keith was the Chief Executive Officer at GETCO and began his career as an options analyst in 1976.