1. it can be used when you don’t want your links to influence the targeted site’s rankings by search engines. That is, the deSTInation of that hyperlink won’t be given any additional weight or cRedit in search result rankings.
For example, let’s say that you have a site selling running sneakers. From the homepage, there are two links within the site. One is a link to About Us page and the other is a link to How To Choose Running Sneakers page. Each of these pages gets 50% of the rank value of the homepage in Google, but you don’t really care about how well the About Us page ranks in search engines. in this case, you can add the rel=nofollow attribute to the About Us link. This will give the full score of the homepage rank value to the second page which contains important contENT for your site.