An in-depth analysis of how PageRank has evolved from a simple search ranking signal to a critical component in Large Language Model (LLM) training and RAG grounding. We explore the math, the history, and the future of link-based authority in the Agentic Web.

“Backlinks are dead!” cries the SEO clickbait. “AI doesn’t need links!” This is technically false. Reports of the backlink’s death are exaggerated, but its role has definitely changed. Discovery vs. Authority In the past, links were for Authority (PageRank). Today, links are primarily for Discovery. Without links, a crawler cannot find your URL to add it to the training set. If you are an orphan page, you do not exist.

“PageRank” is the zombie concept of SEO. It refuses to die, shambling through every forum thread and conference slide deck for 25 years. But in 2025, when checking your “Crawled - currently not indexed” report, invoking PageRank is worse than useless—it is misleading. The classical definition of PageRank was a probability distribution: the likelihood that a random surfer would land on a page. Today, the metric that matters is Indexing Probability.