Google AI
Google has used machine learning in its ranking systems for years. What has changed recently is the visibility of it. AI now shapes search at every level - from how Google understands what you typed to what it shows you at the top of the results page. Understanding these systems is no longer optional for anyone doing SEO.
RankBrain - understanding query intent
RankBrain was Google's first major machine learning ranking signal, introduced to handle queries Google had never seen before. According to Google, RankBrain processes approximately 15% of completely new search queries daily - queries that have no exact historical match in Google's data.
What RankBrain does is interpret the likely meaning of an unfamiliar query by finding the closest match in terms of intent. If someone searches for something phrased in an unusual way, RankBrain maps it to what people usually mean when they ask something similar. The practical implication for SEO is that writing naturally about a topic tends to outperform trying to engineer exact keyword phrases into content - because RankBrain is looking for meaning, not literal matches.
BERT - understanding context within content
BERT (Bidirectional Encoder Representations from Transformers) processes language the way a human reader does - by looking at all the words in a sentence simultaneously rather than left to right. This means it understands that "not" reverses a statement, that pronouns refer to earlier subjects, and that the same word can mean different things in different contexts.
Google applies BERT to both queries and page content. It is why a page optimised purely for a keyword phrase but written awkwardly will underperform a page that covers the same topic in plain, clear language. Google can now tell the difference between content written for a human reader and content written to manipulate an algorithm. The two look different, and the ranking systems reflect that.
AI Overviews - answers above the results
AI Overviews are the generated summaries that appear at the top of Google results for many queries. They pull information from indexed pages, synthesise it into a direct answer, and display it with citations. Google CEO Sundar Pichai announced at Google I/O that AI Overviews now reach 1.5 billion monthly users.
Research by seoClarity found that AI Overviews now appear for 30% of US desktop searches. The queries most affected are informational - exactly the type of content-heavy, explanatory pages that many SEO strategies are built around. A Pew Research Center analysis of 68,000 real queries found a 46.7% relative decline in click rates for results that appear alongside an AI Overview, compared to the same results without one.
The implication is significant. Being indexed and ranking is no longer enough to guarantee traffic. Being cited inside an AI Overview is becoming a meaningful visibility signal in its own right.
What this means for how you write content
All three systems point in the same direction. Google's AI has made it dramatically better at understanding whether content is genuinely useful or engineered for search engines. The SEO tactics that worked when Google was primarily matching keywords - stuffing phrases, padding word counts, thin pages targeting narrow queries - are actively penalised by modern systems.
What these systems reward is content that directly and clearly answers what someone is looking for. Structured pages with clear headings, specific answers near the top of each section, and genuine depth on the topic consistently perform better than content that buries the answer or over-optimises for keywords.
This connects directly to Google's E-E-A-T framework - content that demonstrates real experience and expertise is what all of these AI systems are trying to surface. It also connects to search intent - matching the format and depth of your content to what the searcher actually wants remains the most reliable way to rank, whether it is a human or a machine doing the evaluation.
With the how-search-engines-work chapter complete, the next chapter covers keyword research - where every SEO strategy starts.