AI Vocabulary · 01 The Model
What is Reasoning Model?
A model that generates intermediate working steps before its final answer, trading time and tokens for better results on hard problems.
A reasoning model is a language model trained to produce a sequence of intermediate steps, often hidden from you, before it gives its final answer. This builds on the idea of chain of thought: working through a problem step by step tends to give better results on maths, logic, planning and complex code.
Those extra steps are generated as tokens during inference. That means reasoning costs more and takes longer. Many tools let you set how much effort the model spends, or switch between a fast mode and a thinking mode.
Why it matters for you
Use reasoning where a wrong answer is expensive: analysing a contract, planning a migration, debugging a tricky problem. For quick rewrites or simple questions it mostly adds latency and cost.
Own it
Match the effort to the task. Paying for deep reasoning on every request is like hiring a consultant to sort your inbox.
Where it comes from
The category took shape in September 2024, when OpenAI introduced o1 in Learning to Reason with LLMs: a model trained to work through a long internal chain of thought before answering, with results improving the more time it spends thinking. It builds on earlier chain-of-thought research showing that step-by-step reasoning improves answers, and other labs soon released reasoning models of their own.
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