In link building services, we have this notion of Do Follow and No Follow tags on websites to be linked in. The question arises when Google had changed its search algorithm and did not recognized the links with No Follow tag. In HTML, the No Follow tag on links pertains to opening the link on a new window and will not follow the previous opened link in a new window. In this case, Google had taken this No Follow tags and included it in their algorithm and did not recognized the links with No Follow tags. Suffice to say that this No Follow tag rule will only work on Google and not on other search engines.