How authority actually flows: internal linking and the PageRank patent

Most internal-linking advice is folklore. But the original mechanism is public: US 6,285,999, the PageRank patent. Understanding it changes how you structure a site.

The one-sentence model

PageRank treats the web as a graph and models a "random surfer" who follows links. A page's authority is the probability that the surfer lands on it. Authority flows through links, and each page passes a share of its authority to the pages it links to.

The simplified formula:

PR(A) = (1 − d)/N + d · Σ PR(i)/L(i)

The part that matters for SEO is Σ PR(i)/L(i): a page divides its authority across all its outbound links. More links on a page means each link carries less.

Three practical consequences

1. Reduce dilution on important pages. A page with 150 links passes a tiny fraction through each. Trim navigation and boilerplate links on pages meant to push authority to money pages.
2. Link from your strongest pages. Authority flows from pages that already have it. Your most-linked posts and your homepage are your best internal-link sources — point them at the pages you want to rank.
3. Build clusters, not chains. Group related content and interlink it densely, with a clear hub page. The hub accumulates authority from the cluster and can pass it where you direct it.

What this is not

PageRank is one signal among many, and modern Google layers relevance, quality, and entity understanding on top. But the flow model still holds: links move authority, and structure decides where it goes. Treat your internal links as a budget you allocate on purpose.