What an LLM is (the minimum you need to know)
A Large Language Model (LLM) is a system trained over huge amounts of text that predicts the most likely next word in a sequence. That simplification produces surprising outputs: apparent reasoning, coherent writing and, for what concerns us here, the ability to summarize and cite sources when answering a question. To understand LLM SEO you don't need more theory than this: the model answers based on what it learned during training and, when it can, completes that with real-time searches.
How an LLM chooses what to cite
Three independent signals, weighted depending on the prompt type. Knowing them tells you exactly where to invest effort and where not to.
Signal 1: presence in training data
Whatever your brand has produced or been mentioned in across public sites, books, forums and papers over the past few years is part of the model's knowledge. This signal is retroactive — you can't change what's already there — but you can feed the future corpus with substantive content that gets widely cited.
Signal 2: real-time retrieval (RAG, browsing)
For questions that need fresh information, the model searches the web in the moment. Here you compete prompt by prompt: your indexable site, with recent, well-structured content, enters the race against the rest.
Signal 3: citable content structure
When the model retrieves your page, it decides which fragments to extract. A self-contained paragraph, a clean table or a structured list gets extracted with very high fidelity. A long paragraph full of asides gets ignored or summarized poorly. The shape of the content decides whether you get quoted literally or left out.
LLM SEO strategy 2026 (which signal gets which priority)
Not every signal applies equally depending on stage and brand type. This is the reasonable prioritization for 2026:
| Your situation | Priority 1 | Priority 2 | Priority 3 |
|---|---|---|---|
| New brand or unclear entity | Structure (schema + format) | External authority | Corpus presence |
| Established brand with solid SEO | Structure (reformatting) | Corpus presence (serious content marketing) | External authority |
| Enterprise brand with history | Corpus presence (PR + studies) | Structure (advanced schema) | External authority |
| Regulated market / very technical B2B | External authority (papers, regulation) | Structure | Corpus presence |
Benchmark: how to measure your LLM visibility
Without measurement, the above is theory. The minimum benchmark for it to be serious:
- A battery of 50-200 prompts representative of your category, fixed over time.
- Run against 3-4 engines (ChatGPT, Perplexity, Google AI, optionally Claude).
- Weekly minimum frequency.
- Metrics: mention rate, relative position, sentiment, share of voice, weekly trend.
- Comparison against 3-5 direct competitors.