Rel=nofollow, sponsored, ugc, and the March 2020 hint shift.
The rel attribute set scopes the link relationship to the algorithm. Google introduced rel="nofollow" in 2005 as a strict directive against comment spam. On 2019-09-10 the set expanded with rel="sponsored" for paid placements and rel="ugc" for user-generated content. On March 1, 2020 Google shifted to treating all three as ranking hints rather than strict directives. FTC §255 lives one layer above as the independent disclosure requirement.
Four moves in the rel-attribute timeline.
The attribute set evolved from a 2005 strict directive against comment spam to a 2020 hint-system that scopes intent more than flow. FTC §255 sits beside it as an independent compliance layer.
The 2005 origin: nofollow as a directive against UGC spam.
Google and Blogger introduced rel="nofollow" in 2005 to prevent comment spam from passing PageRank. The mechanic was straightforward: a link carrying the attribute was excluded from the PageRank flow calculation. Webmasters started applying it to internal links to "sculpt" PageRank toward their highest-value pages by hoarding equity by nofollowing low-value outbound links. In 2009 Google modified the calculation to defeat this sculpting: total PageRank is now divided by all outbound links regardless of attribute, but equity is only passed through followed links. The equity assigned to nofollowed links evaporates rather than redistributes.
2019-09-10: rel="sponsored" and rel="ugc" join the attribute set.
On September 10, 2019, Google formally introduced rel="sponsored" for compensated placements and rel="ugc" for user-generated content. The three attributes (nofollow, sponsored, ugc) now describe the relationship between the source page and the link target with more granularity. Sponsored marks paid placements that would otherwise expose the destination to an "Unnatural links to your site" manual action. UGC marks content the publisher did not author, where the platform cannot vouch for the link's editorial intent. Each attribute serves both the publisher (protection from "Unnatural links from your site" manual action) and the algorithm (signal scoping).
2020-03-01: the shift from directive to ranking hint.
On March 1, 2020, Google shifted to treating nofollow, sponsored, and ugc as ranking hints rather than strict directives for crawling and indexing. The practical implication is that partial signal may still pass if the context warrants it. A nofollowed link from a high-authority topically-relevant source may carry attenuated PageRank, feed entity confidence, and contribute to co-citation signal even though the strict 2005 reading would zero the equity. The hint-shift formalized what practitioners had observed: the attributes scope intent more than they scope flow.
FTC §255 lives one layer above the link attribute.
The FTC §255 Endorsements and Testimonials Guides (most recently revised in 2023) require a clear and conspicuous material-connection disclosure on any paid placement containing an endorsement or testimonial element. This is a legal requirement separate from Google's rel="sponsored" requirement. The Dot Com Disclosures guide adds that the disclosure must be proximate to the claim, prominent against distractors, in understandable language, and judged by overall net impression. Suppressing either compliance layer to preserve dofollow signal exposes the buyer's domain to FTC enforcement and to a Google manual action. White-hat methodology meets both layers without trying to launder one through the other.
The link attribute and the anchor signal interact.
A nofollowed link still contributes anchor text to the Penguin 4.0 URL-level distribution scoring; the attribute scopes the PageRank flow, not the anchor signal. A sponsored placement carrying an exact-match commercial anchor still counts toward the per-URL exact-match concentration that Penguin discounts. Anchor distribution discipline applies across the attribute set, not just the dofollow subset.
Methodology questions we get during the audit conversation.
When should I use rel="nofollow" vs rel="sponsored" vs rel="ugc"?
The attributes describe the link relationship. Use rel="sponsored" when the placement involves payment, free product, affiliate compensation, or any other material connection to the destination. Use rel="ugc" on user-submitted content (comments, forum posts, wiki edits) where the publisher cannot vouch for the link's editorial intent. Use rel="nofollow" as the default for cases that don't fit sponsored or ugc but where the publisher does not want to vouch for the destination: outbound links from comments-style sections that don't meet the ugc threshold, or links to pages the publisher cannot evaluate. The rel attribute can carry multiple values (rel="sponsored nofollow" is common on affiliate placements as a belt-and-suspenders signal).
Do nofollow links still pass any ranking signal after the 2020 hint shift?
The March 1, 2020 shift formalized Google's treatment of nofollow as a ranking hint rather than a strict directive. The practical implication is that partial signal may still pass if the context warrants it. The signals that bleed through include co-citation context (peer brand mentions alongside the target), entity confidence via brand-mention scoring (which the May 2024 Content Warehouse leak surfaced), referral traffic that feeds engagement metrics, and topical-cluster proximity that Google reads as part of the broader off-page profile. The exact equity passed is not documented and not measurable in isolation; the practical model treats nofollowed links from high-authority topically-relevant sources as carrying attenuated but non-zero signal.
Do I have to add rel="sponsored" to every paid link?
Yes. The Google guideline requires rel="sponsored" or rel="nofollow" on every paid placement. Suppressing the attribute to preserve dofollow signal exposes the buyer to an "Unnatural links to your site" manual action and the publisher to an "Unnatural links from your site" manual action. The 2020-03-01 shift to ranking-hint treatment does not waive the requirement; it changes how the attribute is read once it is present. FTC §255 adds a second compliance layer: any paid placement containing an endorsement element requires a clear and conspicuous material-connection disclosure independent of the rel attribute. Both layers apply.
Are nofollow links a waste of outreach effort?
No. Nofollow links from authoritative, topically-relevant sources contribute to the inbound profile signal in several ways the algorithm reads. They feed brand-mention scoring via the Panda patent ratio (U.S. 8,682,892). They contribute co-citation context that reinforces topical-cluster authority. They drive referral traffic that feeds engagement signals. They establish the publisher relationship that later converts into dofollow editorial placements. Outreach that demands dofollow as a precondition forfeits all four of these surfaces; outreach that accepts a nofollow placement when the source meets the topical and trust thresholds adds to the profile.
What's the difference between a rel attribute and an FTC disclosure?
They are independent compliance layers. The rel attribute is a machine-readable signal Google's crawler reads. The FTC §255 disclosure is a human-readable statement the reader sees. Google's rel="sponsored" requirement protects the search-result quality; the FTC disclosure requirement protects the consumer from undisclosed endorsements. A paid placement requires both. Adding rel="sponsored" without an FTC disclosure violates §255. Adding an FTC disclosure without rel="sponsored" violates Google's link spam policy. The Dot Com Disclosures guide adds specifics about disclosure proximity, prominence, language, and net impression that govern whether the disclosure is sufficient.
Has anything changed with rel attributes recently?
No new attribute since the 2019-09-10 introduction of sponsored and ugc. The 2020-03-01 hint-shift remains the operative interpretation. The March 2024 link spam update did not introduce new rel attributes but expanded SpamBrain enforcement against scaled placements without compliant rel handling. The May 2024 Content Warehouse leak documented some internal signals tied to link attributes but did not announce any change to the public-facing attribute set. The current operational frame remains: rel="sponsored" on paid, rel="ugc" on user-submitted, rel="nofollow" on default-untrusted, no rel attribute on editorial.
The rel attribute and the FTC disclosure are independent compliance layers.
The audit reads the inbound link profile against both: which placements need a rel attribute change, which need an FTC disclosure layer, and which are correctly scoped already. Inside two weeks.