Also known as: Reasoning LLMs, Chain-of-Thought Models, o1, o3, Reasoning
Reasoning models are a new class of LLM that has shaped the field since the release of OpenAI's o1 in September 2024. They differ from classic chat models in that they work through a multi-stage chain-of-thought before producing the actual answer — either visibly (shown to the user) or hidden (processed internally). The effect is markedly higher answer quality on complex multi-step tasks (mathematical problems, code debugging, strategic analyses). By now all major providers offer reasoning variants: OpenAI o1/o3, Claude Sonnet 4 Reasoning, Gemini Deep Research.
Four practical implications: (1) Source quality matters more — reasoning models assess sources more critically, so low-quality content is cited less often. (2) Structured content has more effect — the multi-step assessment recognises clearly organised arguments better. (3) Factual accuracy is critical — reasoning models check facts against several sources, so factually incorrect statements are more likely to be spotted. (4) Brand authority remains important — reasoning models, too, prefer authoritative sources as a point of verification.
Both classes will continue to exist in parallel. Classic chat models for fast, simple queries (what is X, how do I do Y), reasoning models for complex queries (strategic advice, multi-stage code analysis, multi-domain research). For GEO this means optimisations have to work for both — compact answers for chat, deep structured information for reasoning. Fortunately the optimisation levers overlap by 80 %: clear H2 question-and-answer logic, complete Schema.org markup and factually supported statements work in both classes of model.
Example: A tech magazine tracked its citation rate in OpenAI o1 (reasoning) and GPT-4o (classic) in parallel over 8 weeks. For simple ”what is X” queries the citation rate was very similar (32 % versus 28 %). For complex ”how should I approach X strategically” queries the citation rate in o1 was considerably higher (48 % versus 22 %) — reasoning models prefer sources with structured argumentation, and the publication's own pillar-page style with its dialectical structure was rewarded. Strategic consequence: more argumentative essays in the content mix, fewer purely overview-style listicles.
GEO strategy for reasoning engines
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