PageRank

What is PageRank?

PageRank is an algorithm, developed by Google founders Larry Page and Sergey Brin at Stanford in the late 1990s, that scores the importance of web pages from the links between them. A page is important if important pages link to it. PageRank was the core idea behind Google’s early ranking and is named after Larry Page.

The model imagines a “random surfer” who clicks links at random and, every so often, jumps to a random page instead. A page’s PageRank is the probability that the surfer lands on it. In the original paper, the chance of following a link rather than jumping, called the damping factor, was set at 0.85. Each page splits its PageRank across the links on it, so a link from a page with few outbound links passes more than one from a page with hundreds.

From 2000 Google showed a 0 to 10 PageRank score in its browser toolbar. That “toolbar PageRank” was updated less and less often, and Google removed it in 2016. Its removal did not mean PageRank stopped mattering. Google has since said it still uses PageRank internally, though the modern version has changed a great deal from the original paper and is one signal among hundreds.

Because toolbar PageRank is gone, SEO tools built their own estimates of link authority, such as Ahrefs’ Domain Rating and URL Rating and Moz’s Domain Authority. These are third-party metrics modelled on similar ideas. Google does not use them.

Why PageRank matters for SEO

PageRank is why links matter in SEO at all. It turned the web’s link graph into a measure of trust, and nearly every link-building practice, good or bad, traces back to it.

It also explains several things that still hold. Links from strong pages are worth more than links from weak ones. A page that links out to hundreds of sites passes little to each. Internal links distribute authority around your own site. And links Google decides not to trust, such as nofollow, sponsored or spam links, may pass nothing.

When PageRank was visible, people traded and sold links by their PR score, which led directly to nofollow, Google’s rules on paid links and the Penguin update. Today the safe takeaway is simple: earn links from pages that are themselves trusted and relevant.

PageRank also shaped how Google treats link attributes. When Google introduced nofollow in 2005, the point was to let sites link without passing PageRank. Some SEOs then nofollowed their own internal links to push PageRank towards chosen pages, a practice called PageRank sculpting. Google changed how it handled this in 2009 so that the value of a nofollowed link is simply lost rather than redistributed, which ended sculpting as a tactic.

How to apply PageRank thinking today

1. Prioritise links from pages that have their own backlinks and traffic, not just from big domains.
2. Prefer links in the main content of a relevant page over links in footers, sidebars or long lists of links.
3. Use internal links to send authority from your most-linked pages to the pages you want to rank.
4. Keep important pages shallow in your site architecture, so authority reaches them in a few hops.
5. Ignore anyone selling “high PR” links. Toolbar PageRank has not existed since 2016, and selling followed links breaks Google’s policies.

PageRank example

PR(A) = (1 - d) + d × ( PR(T1)/C(T1) + ... + PR(Tn)/C(Tn) )

d     = damping factor, usually 0.85
T1…Tn = pages that link to A
C(T)  = number of outbound links on page T