What is an ESPP and what can I do with it?

     I have been working for Megacorp Hospital Chain for several years now, and I have failed myself in taking advantage of one of their biggest perks. Not just drinking all the coffee, eating all of the doughnuts and peanut butter and jelly sandwiches, but rather, the Employee Stock Purchasing Program.  
     I guess I didn't try to learn about it sooner because I couldn't figure out why anyone would want to own stocks of the company, as if that was some kind of company gimmick to make employees more invested and work harder. While I still believe that to be true, what I didn't know at the time was that you buy the shares of your company at a 10% discounted rate. Or at least, that is what Megacorp Hospital does. There are no requirements for how long you have to hold onto the stock, and the shares are bought by payroll deduction. You have to use their broker though, which is unfortunate.
     The coolest thing about Megacorp Hospital shares is that they are dividend bearing, not that I plan to make a fortune on it. 
     At the beginning of November I enrolled in the ESPP for a total of 2% of my wages. That may be too much, but I can always sell the stocks and get that extra 10% bonus and reinvest in something else. Which I will no doubt have to do, because one does not want to be too invested in one particular kind of stock, like healthcare.
     Some people would say that the best time to sell your shares of company is on the day you receive them, because one cannot predict volatility in the market. That might be a wise move unless you think your company is only going to increase in value.