Backlink
Definition
From the point of view of the page being linked to, every inbound anchor element is a backlink; the same link is an outbound link to the site that published it. The original insight behind web search was that these links can be counted and weighted: PageRank, described by Page and Brin in 1998, treated a link as an endorsement whose strength depended on the endorsing page's own standing. Modern ranking is far more than link counting, but the principle survives. Not all backlinks are treated alike — a link marked rel="nofollow", rel="sponsored" or rel="ugc" is flagged as one the publisher does not vouch for, and a link's position on the page matters too, with links inside the main content weighing more than ones parked in a footer or a sidebar.
Why It Matters
Links are the main reason a brand-new page can be found at all before anyone searches for it, since a crawler reaches unknown URLs by following links from known ones. They are also the hardest ranking input to fake, which is why they have carried weight for twenty-five years and why so much effort has gone into manipulating them. Google's response has been to devalue rather than punish: since the link spam update of December 2022, links judged artificial are largely ignored, so a hundred bought links can produce exactly zero movement. The flip side is that one link from a genuinely relevant, well-regarded page can do more than a directory full of them, and it also sends real people.
How It Works
A crawler fetching the linking page extracts your URL from the href, queues it, and records the link along with its anchor text and its rel attribute values. Evaluation weighs several things: how the linking site itself is regarded, how topically close it is to the target, where on the page the link sits, and whether the pattern of links to your site looks natural. Repeated links from the same domain add much less than the first one. A nofollow link is a hint rather than a directive as of March 2020, so Google may or may not use it. Google Search Console's Links report shows which external pages it has actually recorded pointing at you, which is usually a shorter list than third-party tools suggest.
Real-World Example
A researcher publishes a dataset summary as a 900 KB PDF at coastal-survey.99helpers.site and mentions it once on a mailing list. A university department page links to the address a week later. That single link is what brings the crawler to a URL nobody had searched for, and 99helpers' cookie-free analytics shows the referral traffic arriving from the department domain in the same week the page first appears in results.
Common Mistakes
- ✕Counting backlinks as a score — a hundred links from thin directories can carry less weight than one from a relevant, well-read page
- ✕Assuming a link disappears if it is nofollowed — it still sends readers, and since 2020 Google treats the attribute as a hint rather than an instruction
- ✕Chasing links to the home page only — the page that needs the endorsement is usually the specific one you want ranked
- ✕Panicking at low-quality links pointing in — unsolicited spam links are normally just ignored, and disavowing is a tool for documented manual actions, not routine hygiene
Related Terms
Anchor Text
Anchor text is the visible, clickable wording of a link. Search engines read it as a short description of the page at the other end, written by whoever placed the link.
nofollow
nofollow is a value in a link's rel attribute saying the publisher does not vouch for the destination. Since March 2020 Google treats it as a hint rather than an instruction.
Internal Linking
Internal linking is the practice of linking from one page of a site to another page on the same site. It is how both readers and crawlers find their way past the home page.
Referral Traffic
Visits that arrived by following a link on another site, identified by the address the browser reports as the previous page. Anything the browser will not name lands in a separate bucket called direct.
Link Sharing
Link sharing means sending someone a web address that points at your file, rather than sending a copy of the file itself. One address, one source of truth, any number of recipients.
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