Common stock, preferred stock, participating or non-participating stock, restricted stock, stock options... all this can be very confusing to a first time founder. Worry not - there are two great resources:
For the new entrepreneur who wants a quick summary, Andy Payne, an angel investor in the Boston area, has a fabulous post explaining everything you need to know about stock and stock options and all that good stuff. This post will give you the vocabulary to ask further questions
For people who want more in-depth treatment of the topic, Goodwin Proctor's Founders Workbench has a comprehensive set of articles on everything about stock and stock options. Take some time to read through it, as it is not the easiest thing to digest.