Nofollow

A meta tag in the HTML code of a web page that tells search engines to disregard the page. On pages such as blog posts that invite user comments, a nofollow link protects you from search engines ranking your page based on user comments you can’t control. Let’s say some users comment on your blog post to promote their products and stuff your comments with keywords. You can use a nofollow tag to avoid search penalties.

Example

A blog post allowing user comments may use a “nofollow” tag in the HTML code for links within comments. This tag tells search engines not to pass any authority from the blog to the linked website, preventing spammy or irrelevant links from affecting the blog’s search engine ranking