"Level 2" is where we can see who is looking to buy (the bid), how many shares they want, and how much they are willing to pay for those shares.

It is also where we can see who is willing to sell (the ask), and how many shares they are offering for what price.

Finally, Level 2 also gives you an idea of what just changed hands......how many shares were just sold/bought and at what pps they were sold at.

Now.....it has a lot more uses, but those are the very simple ones in a nutshell.

It is a good thing to keep an eye on for anyone who is doing some serious buying or selling.