- Links to poor quality content: I found once a page that really performed badly. I discovered that one external link on this page linked to a login page on another website. That’s why I think it is important to add a nofollow when linking to the login page.
- Affiliate links: SInce you earn money in exchange of an affiliate link, affiliate links that pass Google juice are forbidden by the Google webmaster guidelines. You should add a nofollow to affiliate links.
- Links to
badneighborhood: This is when you link your website to a website that has been penalized by Google. Your page or maybe your website traffic can drop because of an external link. That’s why Google suggests adding a nofollow to the signatures of forum members, links inside comments, links inside guestbooks.
- Paid links: This is when you sell links to 3rd parties.