Links and authority
Why links from other websites still matter, how authority scores are estimated, how Site Strength works, and how a local business earns good links.
2 min read · updated 24 September 2026
A link from another website to yours is a public signal that someone found your page worth pointing to. Search engines have used links as a measure of trust since the beginning, and they still matter, though far less crudely than they once did.
What makes a link valuable
Not all links are equal. A useful link is usually:
- From a relevant, trusted site: a trade association, a local newspaper, a supplier, a well-known directory in your industry.
- In context: inside the text of a page about a related topic, rather than in a footer list of hundreds.
- Followed: links marked
rel="nofollow",sponsoredorugctell search engines not to pass standing through them. They can still send visitors. - Earned, not bought. Paying for links that pass ranking value breaks Google's guidelines and can lead to penalties.
Authority scores
Several SEO tools publish a single 0 to 100 number estimating how well linked a domain is. Each tool calculates its own from its own crawl of the web, so the numbers differ between tools, and none of them is used by Google. They are useful for comparing sites against each other with the same tool, not as a target in themselves.
How Site Strength works
Site Strength is our version of that estimate, and we publish exactly how it is worked out.
Common Crawl, a non-profit, crawls billions of pages and publishes a graph of which domains link to which. It ranks every domain by harmonic centrality: roughly, how few link steps it takes to reach that domain from everywhere else on the web. We turn that position into a score on a log scale:
Site Strength = 100 × (1 − ln(position) ÷ ln(number of domains in the graph))
So the best-connected domain on the web scores 100, the 10,000th about 50, and the millionth about 26. A new or local business site that is not yet in the top two million shows as "under 22", which is completely normal.
Because it comes from public data, anyone can check it. It is not Moz's Domain Authority or any other company's score, and it will not match them.
Links a local business can actually earn
- Suppliers and manufacturers often list approved installers.
- Trade associations and accreditation bodies usually link to members.
- Local organisations you sponsor or work with: sports clubs, charities, schools.
- Local news covering a community project, a milestone or useful seasonal advice.
- Well-regarded directories for your trade and area. A handful of good ones beats hundreds of weak ones.
- Useful content such as a genuinely helpful cost guide, which other sites link to as a reference.
Keep track of the links you win
Links disappear quietly: a supplier redesigns its site, a directory listing lapses. Link tracking re-checks the pages that should link to you every day and tells you when a link goes live or goes missing.
Links to avoid
- Networks of low-quality sites that exist only to sell links.
- Automated comment or forum spam.
- Swapping links with unrelated businesses on a large scale.
If you inherited a site with a history of these, a clean-up is worth more than chasing new links.