GEO covers everything that influences how generative engines represent you: crawler access, llms.txt, structured data, entity consistency across the web, citation-worthy content, and the authority signals engines use to pick sources. AEO is often treated as the content-structure subset of GEO.
GEO matters because generative engines increasingly sit at the start of research journeys. A brand the models describe accurately and cite often gets recommended at the moment of decision; a brand they can't read or resolve simply doesn't appear.