The term appeared with voice assistants and featured snippets, when a search engine started answering a question on its own instead of listing pages. The method is the same as today: one question per page or section, the answer in the first sentences, facts that can be checked.
Since 2024 most agencies say GEO, or AI search optimisation, for the work aimed at ChatGPT, Perplexity and Google's AI features. The two words describe one job, and an agency that sells AEO sells the same thing as one that sells GEO.