How PageRank works
PageRank was the idea Google was built on: treat a link as a vote, but weight each vote by the standing of the page casting it. A page linked from many well-regarded pages inherits some of that standing, and can then pass a share of it onward through its own links. The calculation runs round and round the whole web until the scores settle, which is why a link from one strong page can matter more than many links from pages nobody cites.
Two details from the original model still shape how links behave. A page’s value is divided among the links it gives out, so a link from a page that links to very few places carries more than one buried among hundreds. And the value fades as it travels: a page two or three links away from a strong source inherits far less than the page linked directly.
Why PageRank matters
It explains why link building exists at all, and why the same page can rank differently on two sites with identical content. It also explains internal linking. The links inside your own site distribute standing between your own pages, which is why a service page linked from your homepage and from every related article tends to outperform one reachable only from a sitemap.
Understanding the model keeps you honest about link quality. Volume alone was never the mechanism. A handful of links from genuinely respected sites in your field will move a page further than a long list of directory entries, because the weighting was always about who is doing the linking.
Common mistakes with PageRank
The biggest is quoting a number. The public toolbar score Google once published has been retired, and Google gives no way to see the internal figure. Anyone selling links by their PageRank is quoting something that no longer exists.
The related mistake is treating third-party authority scores as if they were PageRank. Metrics from Ahrefs, Semrush, Moz and Majestic are each vendor’s own estimate built from their own crawl of the web. They are useful for comparing one prospect against another, and useless as a target in themselves. Finally, the old habit of sculpting — marking internal links nofollow to hoard value for the rest — stopped working when Google changed its handling so the withheld share is dropped rather than redistributed. It now wastes value instead of concentrating it.
How to act on it
Treat PageRank as a mental model rather than a metric to chase. When you review a potential link, ask whether the linking page is one a real reader would trust and whether the link sits in relevant content, not what number a tool prints beside the domain.
Inside your own site, spend the effort where it is free. Link to your commercially important pages from the pages that already attract attention, use descriptive anchors, and remove the dead ends that trap value in pages nobody needs. Then judge earned links by the traffic and enquiries they bring as well as by any ranking movement. That is the practical version of what link equity describes, and it is the thinking behind sound link building.