AI isn't just changing how marketers work — it's changing how brands get discovered. Generative Engine Optimisation (GEO) is the practice of optimising your content to be selected, cited, and surfaced inside AI-generated answers on platforms like ChatGPT, Perplexity, and Google AI Overviews. This guide breaks down how GEO differs from traditional SEO, how AI engines decide what gets seen, and the four-part framework brands need to build AI visibility — starting today.