TL;DR
- Google added rel="sponsored" and rel="ugc" on 10 September 2019 and began treating nofollow, sponsored and ugc as hints for ranking.
- From 1 March 2020 nofollow also became a hint for crawling and indexing; existing nofollow links do not need to be changed.
- Paid, advertorial and affiliate links should carry sponsored (nofollow is accepted); links in comments and forums should carry ugc.
- noopener and noreferrer are browser settings with no ranking effect, and rel=canonical belongs in the page head, not on anchor links.
Link attributes are values in a link's rel attribute that tell search engines what kind of link it is. For SEO the three that matter are rel="nofollow", rel="sponsored" for paid or affiliate links, and rel="ugc" for links in user-generated content. Since 2019 Google treats all three as hints rather than strict commands, and using the right one on paid links is what keeps a site within Google's spam policies.
What are rel=nofollow, sponsored and ugc?
Each is a value placed inside the rel attribute of an anchor tag, for example <a href="https://example.com/" rel="sponsored">. None of them changes what a visitor sees or where the link goes. They only describe the relationship between your page and the page you link to.
- rel="sponsored" marks links that exist because of payment or another compensation: advertising, paid placements, sponsored posts and affiliate links.
- rel="ugc" marks links inside user-generated content such as comments, forum posts and reviews written by visitors.
- rel="nofollow" is the general-purpose value for any link you do not want to vouch for or pass ranking credit through, when neither of the other two fits.
Values can be combined with a space. rel="nofollow sponsored" and rel="ugc nofollow" are both valid, which is useful because some older search engines and tools only understand nofollow.
When Google changed nofollow from a directive to a hint
Google introduced nofollow in 2005 to fight comment spam, and for years treated it as a directive: a nofollow link was not used for ranking at all. On 10 September 2019 Google announced two changes. It added the sponsored and ugc values, and it said all three attributes would be treated as hints about which links to consider or exclude within Search. From that date the change applied to ranking. From 1 March 2020 nofollow also became a hint for crawling and indexing purposes.
"Hint" means Google may choose to use a nofollow, sponsored or ugc link as a signal, for example to understand a page or discover a URL, instead of ignoring it completely. Google also said there was no need to change existing nofollow links, and that nofollow remains an acceptable way to mark sponsored links, although sponsored is preferred.
Which attribute to use, by link type
The table maps common link situations to the attribute Google's guidance points to.
| Link situation | Recommended attribute | Why |
|---|---|---|
| Paid ad, sponsored article or advertorial link | sponsored (nofollow also accepted) | Paid links that pass ranking credit break Google's link spam policy |
| Affiliate link to a marketplace or merchant | sponsored | The publisher earns a commission when users follow the link |
| Link in a blog comment, forum reply or review | ugc (optionally with nofollow) | The site owner did not write or vet it |
| Editorial link you trust and chose freely | No attribute | A normal link is the correct signal for genuine recommendations |
| Link you must include but cannot vouch for | nofollow | General-purpose value when sponsored and ugc do not apply |
Do nofollow links pass any value?
For ranking, the honest answer is that Google does not disclose how often it uses a hinted link. Because the attributes are hints, a nofollow link can be used in some cases, but no one outside Google can measure how much credit it passes. Plan on the assumption that nofollow, sponsored and ugc links pass little or no ranking credit.
They still have value that has nothing to do with PageRank. A nofollow link on a busy site sends real visitors. A sponsored placement in a relevant publication builds awareness and branded searches. A mention in a forum thread can lead people to your brand even if the link itself is marked ugc. In a link profile, a natural mix of followed and nofollow links is what organic linking tends to look like, since many large platforms mark outbound links nofollow by default.
How to mark up sponsored content without risking a penalty
Google's spam policies list buying or selling links that pass ranking credit as a link scheme. That covers exchanging money, goods or services for links, and sending a free product in exchange for a review with a link. Sponsored content itself is allowed. The fix is to qualify the links in it.
- Add rel="sponsored" to every link in a paid article, including links in the author bio and in images.
- Label the content as sponsored or advertising for readers, which is also a consumer protection expectation in many markets.
- Apply it to affiliate links generated by marketplace tools as well. Many affiliate programmes create links through redirect domains, but the link on your page still needs the attribute.
- If you buy placements, ask the publisher in writing to use rel="sponsored" and check the live page after publication.
A manual action for unnatural links, when it happens, appears in Search Console under Security and Manual Actions. Google's documentation describes both outgoing and incoming link manual actions, and removing or qualifying the links is part of a reconsideration request.
How to audit outbound link attributes on your own site
Search Console's Links report shows which sites link to you and your top linked pages, but it does not show rel attributes. To audit your own outbound links you need a crawl.
- Crawl the site with a desktop crawler such as Screaming Frog SEO Spider or Sitebulb, or a cloud crawler, with outbound link data enabled.
- Export all external links with their anchor text, source page and rel values.
- Filter for links in sponsored sections, author bios, partner pages and affiliate content, and check each has sponsored.
- Check comment and forum templates render ugc or nofollow on visitor links. WordPress adds these to comment author links by default, but custom themes and plugins can change it.
- Look for the reverse problem: editorial links to trusted sources marked nofollow by a plugin rule that applies to every external link. That is not harmful, but it is not accurate either.
- Repeat after major template changes, and at least once a year.
noopener, noreferrer and canonical: what they do and do not affect
Several other rel values show up in the same audits and are often confused with the SEO attributes.
- rel="noopener" is a security value. When a link opens in a new tab with target="_blank", it prevents the new page from accessing the original page through window.opener. It has no effect on rankings. Modern browsers apply this behaviour by default for target="_blank" links.
- rel="noreferrer" stops the browser sending the Referer header, so the destination site's analytics will not see your site as the source of the visit. It also implies noopener. It does not change how Google treats the link, but it can hide referral traffic you send to partners.
- rel="canonical" is not an attribute on a normal anchor link. It is used in a link element in the page head, or in an HTTP header, to tell search engines which URL is the preferred version of duplicate or similar pages. It affects indexing and consolidation, not whether an outbound link passes credit.
What this means for Thai websites
Paid articles and reviews are a normal part of Thai digital marketing: sponsored posts on lifestyle blogs, advertorials on news portals, and product reviews on influencer websites. Each of those links should carry rel="sponsored". Thai publishers and affiliates promoting Shopee and Lazada products through affiliate programmes are publishing sponsored links in Google's sense too. For brands that buy placements, the attribute question belongs in the contract, alongside the fee and the publishing date. For brands building authority, the lesson is to separate two budgets: paid placements for reach, marked correctly, and editorial links earned through content and PR. A link building service should be clear about which is which, and backlink work that relies on unmarked paid links is a risk to the site, not an asset. A technical SEO audit can check outbound attributes across a site, and content marketing is how editorial links are earned without paying for them.
FAQ
What is the difference between nofollow and sponsored?
Sponsored is specifically for paid or affiliate links, while nofollow is a general value for links you do not want to vouch for. Google prefers sponsored for paid links but still accepts nofollow on them.
Should I change my old nofollow links to sponsored or ugc?
No, it is not required. Google said in 2019 that existing nofollow links do not need to be changed. Use the new values for new links where they fit.
Do link attributes affect my rankings directly?
They affect how Google may use the links, not your page's own ranking. Leaving paid links unqualified can lead to a manual action, while correctly marked links carry no penalty.
Does rel="noopener" hurt SEO?
No. noopener is a browser security setting for links opened in a new tab and has no effect on how search engines rank or treat the link.
Do affiliate links need rel="sponsored"?
Yes. Affiliate links are compensated links, so Google's guidance is to mark them sponsored, or nofollow, regardless of whether they pass through a tracking redirect.
If you are not sure whether your sponsored content, affiliate links or purchased placements are marked correctly, Relevant Audience can audit your link attributes and set up a link building plan that stays within Google's policies.
