GEO answers the same question as search engine optimisation, only on a different surface: you are not trying to climb the results list, you are trying to appear as a source inside the summarised answer. The two jobs overlap heavily — what is good for a classic search engine is good for an answer engine too — but GEO has moves of its own.
Why does it matter? Because the shape of traffic has changed: more than two thirds of searches now end without a click, and according to one independent behavioural study, one percent of users click a source inside an AI summary. Appearing is therefore worth something in itself, even when it brings no visitor.
The most common misconception is that there are proven GEO tricks. Controlled measurements contradict most of the received advice, and for many widespread moves there is simply no data at all. What does measurably work: machine-readable structure, quotable claims that stand on their own, and naming your sources.
What there is actual evidence for is the subject of getting cited by AI search, a separate article. The directly related terms: AEO, zero-click and machine-readable.