An external link is a hyperlink on your website that points to a page on a different domain. If your bakery’s allergen page links to the Food Standards Agency, that is an external link from your site. Most SEO people use “external link” for links going out and “backlink” for links coming in from elsewhere.
How external links work
A link counts as external when its destination sits on another domain. A link from yourshop.co.uk to gov.uk is external; a link from your homepage to your contact page is an internal one, and a link between subdomains you own sits in a grey area that search engines tend to judge case by case.
Every outbound link tells search engines two things: that you think the destination is worth a reader’s time, and what you think it is about, through the anchor text you choose. By default a link lets some of your page’s authority flow to the destination. You can change that with a rel attribute:
- rel="sponsored" for paid, affiliate or gifted links.
- rel="ugc" for links added by users, such as in comments or forum posts.
- rel="nofollow" when you do not want to vouch for the destination at all.
Google treats these as hints rather than strict instructions, but leaving them off paid links can be read as taking part in a link scheme.
Why it matters
Linking out is part of writing honestly. If a page on employing staff cites the National Minimum Wage, a link to the current gov.uk rates lets readers check it and protects you when the figure changes. Pages that make claims without showing where they come from are harder to trust, and the trust part of E-E-A-T rests on exactly that kind of evidence.
External links also carry obligations in the UK. Affiliate and paid links are advertising, so the CAP Code expects them to be obviously identifiable to readers, not just tagged in the code. Links to a supplier who pays you commission need both the rel attribute and a clear on-page disclosure.
The fear that linking out “leaks” ranking value is mostly misplaced. A sensible number of relevant outbound links to reliable sources does not harm a page. What does harm it is linking to low-quality or irrelevant sites as part of a swap or a paid arrangement.
Common mistakes
- Nofollowing every outbound link out of habit. It signals distrust of sources you chose to cite and gains nothing.
- Leaving paid or affiliate links untagged. This is the case where rel="sponsored" is expected.
- Linking to competitors’ commercial pages for keywords you want to rank for. Cite an independent source instead where one exists.
- Letting links rot. Government and trade body pages move often; a broken outbound link makes an otherwise useful page look neglected.
- Opening every external link in a new tab without reason. It breaks the back button for many users, particularly on mobile.
How to act on it
When you make a factual claim, link to the primary source: legislation.gov.uk, a regulator, the original study or the official guidance, rather than a blog that summarised it. Use descriptive anchor text that tells readers where they will land. Tag paid and affiliate links correctly and disclose them in plain words on the page.
Run a crawler such as Screaming Frog every few months to catch broken outbound links and redirect chains. Reviewing how pages cite sources, alongside your internal linking, is part of the page-by-page work in my on-page SEO service.