Reasoning Model (Chain-of-Thought)
A reasoning model is an AI language model that breaks complex tasks into several intermediate steps before it produces an answer, rather like thinking aloud (chain-of-thought). Instead of replying at once, it works through those steps either visibly or internally – the chain of thought it shows need not faithfully reflect the internal computation – which costs more computation at request time ("test-time compute") but delivers more reliable results on logic, maths or programming tasks than conventional direct answers.
In practice
Well-known examples are the dedicated reasoning or thinking modes of the large chatbot providers, which set out a route to the answer either visibly or internally before replying. What matters for companies: reasoning models are often slower and more expensive than standard models on simple tasks, but noticeably more accurate on multi-step work such as data analysis, tracking down faults in code or complex content briefs. For short texts or straightforward translation, the extra computation rarely pays off.