Tapatalk is basically an easy way to view and post on internet forums without having to use an internet browser like Internet Explorer, Google Chrome, or FireFox that you would use on your computer. It just makes it a little easier to navigate and use internet forums such as Android Central from your smartphone, especially if you're a member at several different websites.
Feel free to ask more questions. I'll check this thread frequently to help you when I can.
*Sent from work early bcuz some1 4got teh NSFW tag*