Introduced by Google in 2005 to combat link spam, nofollow is an HTML attribute added to a webpage (<meta name=”robots” content=“nofollow”/>), or a specific hyperlink (rel=“nofollow”). It tells search engine crawlers not to follow or pass credit to linked websites as a way to avoid association with spammy content or inadvertently violating webmaster guidelines.
To varying degrees, the nofollow attribute is recognized by all major search engines. Here’s how search engines have explicitly told webmasters to use nofollow:
- On links visitors can add to your site (i.e. in blog comments, forums, reviews, etc.)
- On links from ads that appear on your site
- On links included in online press releases
- On links contained within code or widgets embedded on your site that point to another’s site