Glossary
What is the rel attribute on a link?
The rel attribute is the part of an HTML link that describes the relationship between the current page and the linked one. For SEO, the values that matter are nofollow, sponsored and ugc. Others, such as noopener and noreferrer, are for security and privacy and don't affect how search engines treat the link.
The values that matter for SEO
| Value | Use for | Since |
|---|---|---|
nofollow |
Links you don't vouch for | 2005 |
sponsored |
Paid links, ads, affiliate links | 2019 |
ugc |
User-generated content: comments, forums | 2019 |
Google treats all three as hints. You can combine them: rel="sponsored nofollow" is fine and helps older systems that only know nofollow.
Values that don't affect ranking
noopener: stops the new tab from accessing the original page, a security measure fortarget="_blank"links.noreferrer: hides the referring page from the destination, which also hides the visit's source in their analytics.external,me,author: descriptive values with no ranking effect.
A directory link with rel="noopener" only is still a followed link. One with noreferrer won't show as referral traffic in your analytics, so use UTM parameters to measure it.
Example
A directory link reads rel="nofollow noopener noreferrer". It's nofollow for SEO, safe for security, and invisible as a referrer, so the founder adds UTM tags to the URL in the listing to see the visits.
FAQ
Does noopener make a link nofollow?
No. noopener is a security value only.
Can I use sponsored and nofollow together?
Yes. Combining them is allowed.
What happens if a paid link has no rel value?
It passes ranking credit, which Google's spam policies count as a paid link scheme.