What it is
An LLM is a prediction machine for language. It was trained on a large slice of the internet and books to learn how words and ideas fit together, so it can continue a sentence, answer a question, or summarize a page in a way that sounds human. It does not look things up the way a database does. It generates a likely response based on the patterns it learned.
Why it matters
LLMs are the AI systems audience. When someone uses ChatGPT, Claude, Perplexity, or Google AI Overviews, an LLM is the thing reading the web and deciding what to say about your category. Two traits matter for marketers. First, an LLM's training has a cutoff date, so it does not automatically know recent or niche facts. Second, it can sound confident while being wrong. Both are why how your content is written and structured now shapes what these models say about you.
What to do
Make your content easy for a model to read and trust. Write plainly, state facts directly, and keep them consistent across your site so a model is not weighing contradictions. For anything recent or specific, the model usually relies on retrieval, so structure pages to be pulled cleanly. Run WAIO Engine to see how legible your site is to the models behind AI search.