Reasoning model
Also called thinking mode, extended thinking, reasoning mode
A model that writes out its working before answering. It helps on multi-step problems and costs time and allowance.
A reasoning model, or a model in thinking mode, doesn't answer straight away. It first produces working: breaking the problem down, trying an approach, checking it, sometimes backtracking. Only then does it write the reply you see.
That helps most where several steps have to come out right: a sum with conditions, a tricky bug, a comparison with trade-offs. It helps little with simple questions, or with anything that depends on recent facts, where a web search matters more. And it isn't free: thinking takes longer and uses more of your allowance. On some tasks, thinking for longer even makes answers worse.
For example
"Which of these three phone plans is cheapest over two years if I add a second line in month eight?" is a thinking-mode question; "What's the capital of Peru?" isn't.
Put it to use
Where you'll meet reasoning model in ChatGPT, Gemini and Claude, how to use it there, and the mix-up most people make.
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