The group of people most interested in your product or service would be known as your prospects, being able to reach out to this group of people is very important and you need the right knowledge to make this happen online. The first step would be to think of all the places they frequent on the Internet. A good example of such a place would be an online forum, there are forums for just about every industry you can imagine and its safe to say that your prospects can be found in a particular forum.