LLMs are neural networks with billions of parameters trained on massive text corpora. They learn statistical patterns of language and can generate coherent text, answer questions, summarize, translate, and reason.
Major LLMs in 2026
- GPT (OpenAI): the engine behind ChatGPT and ChatGPT Search.
- Claude (Anthropic): used in Claude.ai and via API.
- Gemini (Google): the engine behind Google AI Overviews and Bard.
- Llama (Meta): open-source family of models.
- Perplexity: doesn't train its own models but combines multiple LLMs with real-time search.
Why LLMs matter for SEO
LLMs are trained on snapshots of the web. Brands with strong presence, quality content, and structured data are internalized as model "knowledge" — being cited even when the user doesn't navigate to the site. It's the new format of visibility.