links
PageRank by Larry Page and Sergey Brin, is the foundational algorithm Google was built on - it ranks web pages by treating hyperlinks as votes, where a link from a high-authority page passes more "link juice" than one from a low-authority page. The model calculates a probability-based score reflecting how often a random web surfer would land on any given page by following links. Explains why backlink quality and site authority matter in SEO, and why links from authoritative sources carry disproportionate ranking value.
Google’s Reasonable Surfer model represents a shift from a purely topological "Random Surfer" PageRank to a behaviourally-informed weighting system that assigns non-uniform probability to links based on their visual and structural attributes. By analysing feature data - including link position (main content vs. footer), font size, colour contrast, and anchor text length - the algorithm determines a "click-weighted" influence for each citation, ensuring that prominent, contextually relevant links pass more equity than obscured or boilerplate elements. Implies that durability is no longer a simple function of link quantity, but rather a result of probabilistic engagement signals where the value of a backlink is directly tied to its navigational salience and the likelihood of it being selected by a "reasonable" human user.
Google's original 1998 paper introduces a large-scale hypertext web search engine architecture built around two core innovations: a distributed crawling system and a link-based ranking algorithm called PageRank. PageRank computes a page's importance by recursively weighting inbound hyperlinks from high-authority sources, operationalising the citation-graph model of academic literature into a quantifiable 0–10 relevance score calculated across the entire crawled web graph. This anchor-text-plus-PageRank coupling directly challenges pure TF-IDF retrieval models by injecting external link topology into ranking decisions, meaning search systems that index content in isolation without modelling inter-document authority signals will systematically mis-rank high-quality pages against keyword-stuffed low-quality ones.