Large language model (LLM)
Also known as: LLM, Large language model, language model
A large language model is a machine learning model, typically with several billion to a trillion parameters, trained on vast collections of text from the web, able to understand and generate natural language. Such models are the technical foundation of every modern AI search engine — ChatGPT, Gemini, Claude, Perplexity — and of chatbots generally. They use a transformer architecture, introduced in the 2017 paper "Attention is All You Need", and are refined through pre-training, fine-tuning and reinforcement learning from human feedback.
How they generate text
A language model predicts the next word, or token, over and over, based on the context so far. For a search query, relevant web sources are fed in as well through retrieval-augmented generation: the model "reads" the sources, writes an answer and can link back to them. One point deserves emphasis: these models do not understand in the human sense, they produce statistically likely text. They can be factually wrong — the phenomenon known as hallucination — which makes citing sources all the more important on consequential topics.
Pre-training, fine-tuning and human feedback
- Pre-training — the model learns to predict the next token across enormous web corpora: Common Crawl, Wikipedia, GitHub, academic papers. This is where its knowledge of the world settles.
- Fine-tuning — targeted further training for particular domains such as code, medicine or law.
- Reinforcement learning from human feedback — human raters judge answers, and the model learns to be more helpful, more courteous and safer.
What this means for GEO
The implication matters: language models "know" domains that appeared in pre-training or fine-tuning better than unfamiliar ones. A brand cited frequently in authoritative sources — Wikipedia, Wikidata, major publishers — is treated intuitively as reliable. Brand building has therefore become a GEO lever in its own right. A domain with a clear Wikidata entity, Schema.org markup and consistent author bylines is far likelier to be judged a citable source than a technically similar domain without those signals.
Example from practice
Example: A specialist blog with no distinct brand identity held solid top-ten rankings in Google yet was practically invisible in ChatGPT's answers. After creating a Wikidata entity for the brand, adding complete Organization schema with sameAs references to its social profiles and Wikipedia, and giving its six main editors consistent bylines, the domain was named in ChatGPT answers for 9 of 14 core topics within five months — up from one in fourteen. Its classic Google visibility had barely changed; the gain came entirely from building the brand as an entity.
Frequently asked questions
What is a large language model?
How does it differ from earlier language technology?
Where are they used?
How are they trained?
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GEO optimisation for LLM engines in Rankmio
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