A nofollow link is a hyperlink marked with the rel="nofollow" attribute to tell search engines the source page does not endorse the destination for ranking purposes. In HTML, it looks like this: <a href="https://example.com" rel="nofollow">Example</a>. The link still works for users, sends them to the destination when clicked, and looks identical in the browser. What it changes is the signal sent to crawlers.
That distinction matters more than it used to. In September 2019, Google reframed nofollow from a strict command into a hint, alongside two newer values, sponsored and ugc. The attribute was originally introduced to fight comment spam, but its modern role is broader: it describes the relationship between two pages, and search engines now weigh that description rather than obey it blindly.
The rest of this guide walks through the markup, the modern interpretation, and the practical cases where nofollow is the right call.
How Nofollow Works in the HTML
The rel attribute sits inside an anchor tag, the <a> element that creates any hyperlink, as defined in the HTML reference documentation for the element. Its job is to describe the relationship between the page the link lives on and the page it points to. nofollow is one of several possible values; sponsored and ugc are the other two commonly used in SEO.
A followed link, the default kind, has no rel value at all, or in some CMS setups, a rel of dofollow. A nofollow link is explicitly marked. Crawlers read the source, see the value, and use it to adjust how they handle the link for crawling, indexing, and ranking calculations. None of that changes what the user sees. The link is still clickable, still sends traffic, still renders the same in a browser.
For SEO, the practical question is what the engine actually does with the signal. Older guidance treated nofollow as a wall: do not crawl, do not count, do not pass value. The current guidance treats it as input the engine weighs rather than a command it must obey.
Why Nofollow Is a Hint, Not a Command
Google announced the change in September 2019 in a post titled “Evolving nofollow”, part of a broader effort to recognize more link relationships. The new framing: nofollow, sponsored, and ugc are all hints about how a link should be treated, not absolute instructions. Search engines can still choose to crawl or even index a page that is reached only through nofollowed links. The attribute is now a piece of information the engine weighs, not a switch that hides pages from it.
What that means in practice: a nofollow link may still be discovered and indexed if the destination is reachable from other sources, and the linking page is signaling that it does not want to vouch for the destination in a ranking sense. The intent of the link, who placed it and why, is what nofollow is communicating. That signal still carries weight, even if it is no longer absolute.
When You Should Use Nofollow
The cleanest way to decide is to classify the link before you publish it. The most common cases fall into three buckets.
Paid and sponsored links
Any link placed in exchange for money, product, or other compensation should be labeled so the engine knows the relationship, per search engine guidance on qualifying outbound links. The most specific signal is rel="sponsored"; rel="nofollow" can be added alongside it for extra caution.
- Use
rel="sponsored"for affiliate links, paid placements, and review programs where compensation was provided. - Combine with
rel="nofollow"(i.e.,rel="sponsored nofollow") when you want the most conservative signal possible.
User-generated content
Comments, forum posts, and profile links are the spots most vulnerable to spam. The most specific value here is rel="ugc", and many sites also add nofollow as a second layer of defense. Most modern CMS platforms and forum software apply this automatically to any link a user submits.
Untrusted or unvetted destinations
If you need to cite a source you cannot stand behind, for example a competitor’s questionable claims referenced in a critical review, nofollow is the safer default.
Want a clearer picture of how rel values shape your site’s link profile? Clickside can map your outbound and UGC links and show you which ones need updating.
How to Tell If a Link Is Nofollow
The fastest way to check a link is to look at the underlying HTML. Right-click the link in a browser and choose “Inspect” (in Chrome, Edge, or Firefox) or “View Page Source” to see the markup. The full anchor tag will be visible, and you can scan it for rel="nofollow", rel="sponsored", rel="ugc", or any combination.
What you are looking for is a rel attribute on the <a> tag. If the tag has no rel attribute at all, the link is followed by default. If it shows rel="nofollow", that is the signal. And remember: spotting the attribute does not mean the destination page is invisible to Google. The rel value is a signal the engine reads, not a block.
Putting Nofollow to Work
Treat nofollow as a label for the relationship a link represents, not a switch that hides pages. The most useful habit is to classify outbound links by purpose before publishing: editorial links stay followed, compensated links get sponsored, community links get ugc, and anything you cannot vouch for gets nofollow as a fallback.
One practical next step: open your site, sort your outbound links by source (your own content, user comments, sponsored placements), and check that each one carries the rel value that matches its purpose.
Ready to clean up your link attributes the right way? Let Clickside audit your site and apply the correct rel values where they count.