Link building glossary

Link attributes

Link attributes are rel values added to a link's HTML to tell search engines what kind of link it is. Google recognises three: sponsored for paid or advertising links, ugc for user-generated content such as comments and forum posts, and nofollow when neither applies. Google treats all three as hints.

Reviewed by Gareth Hoyle, Managing Director
Last reviewed 31 October 2026

When were sponsored and ugc introduced?

The nofollow attribute was introduced in 2005 to help fight comment spam, and Google soon recommended it for advertising links too. On 10 September 2019 Google announced two new values, sponsored and ugc. Until then, Google did not count nofollow links as a signal in its algorithms. From that day all three values became hints for ranking, and for crawling and indexing nofollow became a hint on 1 March 2020. Google said links still carry useful information, such as how the words in a link describe the page it points to.

Which attribute should I use?

Values can be combined in a space- or comma-separated list, such as rel="ugc sponsored".

rel="sponsored" for adverts, sponsorships and other paid placements; nofollow is still acceptable but sponsored is preferred
rel="ugc" for links in comments and forum posts, which can be removed for trusted, regular contributors
rel="nofollow" when you want to link without implying endorsement and the other values don't fit

What about paid links?

Google's spam policies say buying and selling links for advertising or sponsorship is not a violation as long as the links carry rel="nofollow" or rel="sponsored". A paid link without either is link spam and risks a manual action. Google says the only wrong choice is leaving a paid link unmarked: tagging an ordinary link as sponsored at most means it might not pass credit.

Dofollow is not an attribute. It is industry shorthand for a link that has none of these values.

Example

A travel blog paid to review a hotel adds rel="sponsored" to the booking link. The blog's comment system adds rel="ugc" to links readers post. A link to a forum thread the writer mentions but does not vouch for could use rel="nofollow".