LLM – what a large language model is and what it means for SEO and websites

Definition

An LLM (large language model) is an AI model trained on large amounts of text to understand, generate and summarise natural language, for example in chatbots and AI-based search services.

An LLM (large language model) is an AI model trained on enormous amounts of text. It understands and generates language by predicting what is likely to come next – word by word. ChatGPT, Claude and Gemini are all powered by LLMs.

How an LLM works

Unlike a search engine, an LLM has no index of the web. It does not look answers up. Instead, during training it learns patterns, connections and turns of phrase from the text it is fed, and it uses those patterns to generate answers.

That explains both its strength and its weakness. An LLM can phrase and summarise fluently, but it can also give wrong answers with complete confidence – known as hallucination – when the patterns point the wrong way.

Two ways an LLM encounters your content

• Training data – content the model learned from during training. That data is frozen at a particular point in time and is not continuously updated.
• Real-time retrieval – when an AI service fetches live pages at the moment the question is asked – through a search function, for example – and bases its answer on them.

When it comes to visibility, the second is the one you can mainly influence. When an AI retrieves sources on the fly, your website as it stands today – its structure, clarity and credibility – decides whether the content is used.

What an LLM means for SEO

An LLM does not read a page the way a visitor does. It interprets concepts, relationships and how credible a source appears. That makes fragmented SEO – where each page is optimised in isolation – less effective.

What wins instead is coherent knowledge: consistent terminology, clear definitions and content that hangs together in topic clusters. A model that understands what your company is, and sees that confirmed in several places, will find it easier to describe you correctly.

LLMs are changing how websites are built and run

The impact does not stop at visibility. LLMs are also changing the work behind a website – how it is built, updated and maintained.

AI-assisted development means code and content can be produced considerably faster, with people still acting as strategists and quality reviewers. We explain how that works in AI-assisted web development.

The bigger shift is MCP (Model Context Protocol), a standard that lets an LLM connect directly to other systems. Connected to a CMS, the model can actually read and update pages, not just suggest text in a chat window. A post can be researched, written and published in one flow.

That turns AI from a writing tool on the side into part of how the website is actually run. For us at SEOS, this is not a vision of the future – we already work this way with Webflow and headless CMSs. There is more on what that means in MCP for websites.

Being visible to an LLM

The work of getting cited and accurately represented by AI is called AEO (answer engine optimization). It rests not on tricks but on clear, well-structured expert knowledge that a model can trust.

We look at how this affects search work as a whole in How is SEO affected by AI? and AI SEO 2026.