You get the basic idea of what is robots.txt now. Visit your webmaster tool in google account and you find option of robots.txt. You can control the links you don't wanna be ready by google bots.
Google hadn't updated 3 google penguin but they update different 3 algorithm. First one is Google Panda updated in September 2012 after that second and third was updated in October 2012. Second is called Google penguin update and third one is called Page layout Algorithm update.
@peterjohn12345 This tool allows you to indicate to Google which links you would like to disavow, and Google will typically ignore those links. Much like with rel=”canonical”, this is a strong suggestion rather than a directive—Google reserves the right to trust our own judgment for corner cases, for example—but we will typically use that indication from you when we assess links.