What Is the Nofollow Tag?
The nofollow tag is an HTML attribute applied to a hyperlink — <a href="https://example.com" rel="nofollow"> — that instructs search engine crawlers not to pass link equity (PageRank) through that link to the destination page. Introduced by Google in 2005 to combat comment spam, the nofollow attribute signals: "We're linking to this page, but we're not vouching for it."
When Google encounters a nofollow link, it treats it as a hint (not a strict directive, following a 2019 policy update) to not crawl that link or pass ranking credit through it. The distinction between hint and directive matters: Google may still choose to crawl a nofollow URL and index the destination page, but it will not flow authority through the link in its link graph calculations.
Two related attributes were introduced alongside the 2019 update: rel="sponsored" for paid or affiliate links, and rel="ugc" for user-generated content (comments, forum posts). All three are variations of the same concept — link-level instructions that modify how search engines treat outbound equity flow. Using the right attribute for the right context is both an SEO best practice and a requirement under Google's link spam policies.
Why the Nofollow Tag Matters for Marketers
Understanding nofollow is essential for two reasons: protecting your site's link profile and interpreting the value of links you receive.
When you link out to external sites without nofollow, you distribute some of your domain's accumulated link equity to those destinations. For a high-authority site, this creates an incentive for spammers to solicit links in comments, forums, and user-generated sections. Applying nofollow to all user-generated links prevents this exploitation without requiring editorial review of every user submission.
For paid links and sponsorships, the stakes are higher. Google's guidelines explicitly prohibit passing PageRank through paid link placements. Failing to mark sponsored links with rel="sponsored" or rel="nofollow" risks a manual penalty — a direct downgrade in the site's ranking ability. This applies to affiliate links, sponsored posts, and any link exchanged for compensation.
From the receiving side, not all backlinks are equal. A followed link from a high-authority site passes ranking credit. A nofollow link from the same site doesn't pass credit directly — but it can still drive referral traffic, brand awareness, and indirect authority signals. Monitoring whether your most important backlinks are followed or nofollow affects how you assess your link building results.
How to Implement Nofollow Tags
- Apply nofollow to all user-generated link areas. Comment sections, forum posts, review submissions, and user profile pages should have nofollow set programmatically for all links. Most CMS platforms do this by default.
- Use rel="sponsored" for paid placements. Any link exchanged for money, products, or services must carry this attribute. Apply it to affiliate links, sponsored blog posts, and advertorial links.
- Use rel="ugc" for community content. Q&A sites, community platforms, and review systems benefit from this more specific attribution.
- Audit external links periodically. Use Screaming Frog or a link auditing tool to identify external followed links in content areas that should be nofollow — especially older content that predates your nofollow policies.
- Don't overuse nofollow internally. Some sites mistakenly add nofollow to internal links, which disrupts PageRank flow between their own pages. Internal links should almost always remain followed.
How to Measure Nofollow Impact
Tools like Ahrefs and Semrush differentiate between followed and nofollow backlinks in their link indexes, allowing you to see the ratio of followed-to-nofollow in your backlink profile. A healthy profile will have a majority of followed links; a profile skewed toward nofollow (which might result from heavy reliance on forum posts or directory submissions) carries less ranking power.
Monitor your own outbound link profile with Screaming Frog — export all external links and filter by rel attribute to confirm your nofollow implementation is applied consistently.
Nofollow Tags and AI Search
AI-generated search responses aren't directly governed by the nofollow attribute — AI systems that retrieve web content for citation don't primarily use the link graph to determine source authority. However, nofollow links still matter in the AI search context indirectly: Google's domain authority calculations (informed in part by followed backlinks) influence which sites appear prominently in AI Overviews. Sites with strong followed-link profiles carry more authority into AI retrieval systems. Protecting that authority through proper nofollow implementation on paid and UGC links maintains the integrity of your domain's ranking power in both traditional and AI-augmented search.