Answer:
Doing your Due Diligence, simply means doing your homework on a company before investing in its stock.
You really want to look at the company's financial statements to see if the company is doing well. If it is on the verge of bankruptcy, you really should stay out of investing in it.
Due Diligence can include, but is not limited to:
-Reading past press releases by the company for positive or negative news that might affect the price of the stock.
-Look to see if there is a large daily average of traders trading the stock on any given day.
-Make sure that there is a high volume of trades per day, you don't want to buy a stock and get stuck with it because there are no traders wanting to buy the stock.
-Call the company, make sure you get an answer, and research their address to make sure that they are a real company and not just some shack in the middle of a desert road, incorporated in Nevada, selling stocks that are not even worth sand they are built on.
Due Diligence is doing anything and everything in your power and control to ensure that your invested dollars, euros, yen, etc. are in good working hands.