Reasoning model
A reasoning model is a language model trained to work through a problem in intermediate steps before giving its final answer. It is usually slower and costlier per question, but better at maths, coding, planning and multi-step logic.
In one line, for a 12-year-old
A reasoning model is an AI that "shows its work" in its head before answering.
An example
Choosing a "thinking" or "extended reasoning" mode in a chatbot before asking it to plan a week of school lunches within a budget.
Why it matters to people
Step-by-step reasoning looks convincing, but the steps can still contain errors. For decisions that matter, check the conclusion, not just how confident the reasoning sounds.