What are backlinks?

Why search engines count links

In 1998, Stanford students Sergey Brin and Larry Page published the idea behind Google: rank pages not only by their words, but by the links pointing at them. Their PageRank model imagines a “random surfer” who keeps clicking links. Pages where the surfer ends up most often are the most important. A link from a page the surfer visits a lot is worth more than a link from a page they rarely reach.

That 1998 paper is heavy going, all matrices and eigenvectors. ahaboo takes the opposite route with ideas like why the Moon has phases, narrating each step while you move the pieces yourself.

Google now uses hundreds of signals, but links are still one of them. Its own documentation says it uses links “as a signal when determining the relevancy of pages”.

What the model shows

• Quality beats count. One link from the well-linked Popular guide lifts your page more than a link from the Tiny blog that nobody links to.
• Links are shared, not copied. A page with twenty outbound links gives each one a twentieth of its vote. That’s why a link from a focused article can outweigh one buried in a sitewide footer.
• Nofollow drops the share. Mark a link nofollow and its slice isn’t redirected to the other links; it simply leaves the system. That’s the behaviour Google described in 2009 when it ended “PageRank sculpting”.
• Your links out cost you little. Switch off your page’s outbound link and your own score barely moves. Linking to good sources is not “leaking” rank in any way that matters.

This is the textbook 1998 model, simplified. Google’s current ranking is far more complex and not public.

What makes a backlink valuable

• Relevance. A link from a site on the same subject is a clearer signal than one from an unrelated directory.
• The linking page’s own links. As the model shows, a page that is itself well linked passes more.
• Editorial placement. A link in the body of an article, chosen by its author, beats one in a comment or a paid widget.
• Anchor text. Descriptive anchors tell search engines what the target is about. Check yours with the anchor text checker.
• Follow status. A followed link is a full vote; nofollow, sponsored and ugc links are hints to count it less. See the nofollow checker.

How to check your backlinks

To list who links to you, you need a data source that has crawled the web: Google Search Console, Bing Webmaster Tools, or a commercial index such as Ahrefs. Once you have a list of linking pages, the backlink verifier confirms each link is still live, still followed, and still uses the anchor you expect.