External Link
An external link is a hyperlink that points from a page on your site to a page or resource on a different domain. It gives readers trust and context, and its rel attribute can signal the nature of the link to search engines.
- An external link is a hyperlink that leaves your site for another domain, which makes it effectively synonymous with an outbound link.
- It points in a clearly different direction from an internal link, which connects pages within the same domain, and from an inbound link (backlink), which other sites point at your content.
- Citing authoritative sources reinforces the trust and context of your content, and Google itself recommends external links as a way to add value for users.
- Best practice is to mark advertising, paid, and user-generated links with
rel="sponsored",rel="ugc", orrel="nofollow"to convey their nature.
What an External Link Is
An external link is a hyperlink that connects one page on your site to a page or resource hosted on a different domain. Ahrefs defines it as a hyperlink that points to a page or resource outside of a given website and describes it as the opposite of an internal link, which stays within the same domain.
It helps to recognize that the same link gets different names depending on whose perspective you take. A link leaving your site is both an external link and an outbound link, but from the standpoint of the site it points to, that same link is an inbound link coming in, in other words a backlink. As Ahrefs puts it, one site's external link counts as another site's backlink. An internal link, by contrast, only connects pages within the same domain, so its direction and purpose are distinctly different from those of an external link.
The core value of an external link lies in giving users trust and context. When you link out to the statistics, original texts, and official documents that support your claims, readers can verify the information and your content gains authority. Google's John Mueller has noted that linking to other websites is a great way to provide value to your users.
Best Practices
Citing Authoritative Sources
External links work best when they point naturally to relevant, trustworthy material. Citing official documentation, primary data, and resources from authoritative organizations strengthens the credibility of your content. On the common belief that linking out drains your own ranking authority, Ahrefs states plainly that there is no evidence to support it, so you can link to valuable material without hesitation.
Signaling Link Nature with the rel Attribute
Not every external link represents an editorial endorsement. Google recommends distinguishing the following rel attribute values according to the nature of the external link.
| Attribute | Purpose | Applies to |
|---|---|---|
rel="sponsored" | Marks advertising and paid links | Paid placements, advertisements |
rel="ugc" | Marks user-generated content links | Comments, forum posts |
rel="nofollow" | When no value above fits and you do not want association or crawling | Untrusted sources |
Google advises marking paid links with the sponsored value when they are advertisements or paid placements, and marking UGC links such as comments and forum posts with the ugc value. The nofollow value is used when no other value applies and you would prefer Google not to associate your site with the link or crawl the linked page.
One point worth keeping in mind is that, since September 2019, these attributes are treated as hints rather than directives. Google's documentation states that links marked with these rel attributes generally will not be followed, which signals a processing hint rather than a guarantee. For an ordinary editorial external link, then, it is appropriate to leave it as a normal followed link rather than adding nofollow.
External Link Code Examples
<!-- Citing an authoritative source: a normal followed link -->
<a href="https://example.com/research">Official research</a>
<!-- Paid or advertising link -->
<a href="https://sponsor.example" rel="sponsored">Sponsored page</a>
<!-- Link inside a user comment -->
<a href="https://user.example" rel="ugc">User-recommended link</a>Basis
The definition above and the purposes of the rel attribute values draw on Google Search Central's guidance on qualifying outbound links and on the External Link entry in the Ahrefs glossary. The note that rel attributes have been treated as hints since 2019, along with the distinction among internal, external, and inbound links, is likewise confirmed in those same sources.