Users can freely add hyperlinks to each of those places, and due to their length, it isn't always actually sensible to moderate every unmarried one of those hyperlinks. So, so that it will deter hyperlink spammers from taking gain of a site's PageRank, the web page will often select to apply the nofollow characteristic to all links posted by using different customers.
Another use for the nofollow characteristic is for advertisers to use on hyperlinks which have been paid for. So, if you purchase an advertising and marketing banner on a internet site which links to you, Google says that the nofollow attribute ought to be introduced so that they understand not to bypass any PageRank across that hyperlink.
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