Good question! We are in the process of updating "Follow" feature. Currently, when you follow someone it was like putting them in a list you could go to. In the next day, you will start getting alerts on the site and by email if 1) you want them, and 2) when they post something (topics only). You can also follow someone's post by "Favoriting" it. Then, when someone else comments on it, you can see what they wrote. We may follow up with some other features to make it easier to find and follow categories and (hash)tags.