Outbound link
An outbound link, also called an external link, points from your page to another site. Linking out does not hurt a page: Google has said repeatedly that citing sources is normal, and its guidance on helpful content expects pages to say where facts come from. The rules that matter are about which links and which rel values.
By Théophile Louvart, founder of Porteur · Updated 15 September 2026 · Markdown
The four rules worth keeping
- Link to the primary source, not to someone quoting it. If a figure comes from Google’s documentation, link the documentation.
- Mark paid and affiliate links with rel="sponsored", and links submitted by users with rel="ugc". Selling links that pass ranking is a link scheme.
- Check them occasionally. Sites die, pages move, and a guide full of dead links reads as abandoned.
- Open in the same tab unless the reader is mid-task. That is a usability choice, not a ranking one.
<a href="https://developers.google.com/search/docs">Google's documentation</a>
<a href="https://partner.example.com" rel="sponsored">our sponsor</a>Why people fear linking out
The fear comes from the PageRank metaphor: a page divides its value among its links, so an outbound link is value leaving. That division is real and the conclusion is wrong.
A page that cites nothing is not a stronger page, it is a less trustworthy one. Sources are one of the visible signs of the experience and expertise that Google’s quality guidelines describe, and an assistant that quotes your page looks at the same thing.
What to do on a product site
Cite what you claim
Every number that is not yours gets a link to whoever published it. Every quote gets its source.
Do not link a rival for the sake of balance
Link them when the reader needs them, on a comparison page for example. That is honest and it is the page they came for.
Sweep for dead links each quarter
Run a broken link check over the library and fix or drop what has died.
Keep affiliate and sponsored links marked
One attribute, applied where money is involved, keeps the whole site out of an argument.
Questions
No. Google has said that linking to sources is normal and useful. A page with no citations is harder to trust, both for a reader and for an assistant deciding what to quote.
Only when they are paid, affiliate or user-submitted. Use rel sponsored for paid links and rel ugc for user content. Editorial links need no attribute.
There is no threshold. The test is whether a reader would follow each one. A paragraph with five links to the same source is noise; a guide with twelve sources across two thousand words is well cited.
It is a usability decision. Opening in a new tab helps when the reader is mid-task, such as following a checklist. It has no effect on ranking.
Nothing automatic, but the page ages badly and readers hit dead ends. Check the library each quarter and replace or remove what has gone.
Check my site, free
The free check reads the links on your pages, in and out, and names the dead ones and the pages nobody links to, in about thirty seconds.
- Free check, no card
- Read-only, your own accounts
- Readable by your agent