Getting an AI to write out its steps one by one before it gives the answer.
Chain of thought (CoT) means having an AI write out its in-between steps before the final answer. Each step supports the next, so it makes fewer mistakes on problems that need several steps.
In 2022, a Google team showed that adding a few worked examples to a prompt sharply raised scores on math word problems. Another 2022 study found that simply adding "Let's think step by step" helped too.
Reasoning models are trained to do this on their own. But research suggests the written steps don't always show how the model really reached its answer.
Think of it like this
It's your teacher saying, "Show your work." Writing each step makes mistakes easier to catch, and you're less likely to skip something important.
For example
Ending a question with "Think it through step by step" is the simplest chain-of-thought prompt.
Records about this
Source-checked moments from AI history.
CoT without examples. The original of every later zero-shot reasoning prompt
The starting point of the entire lineage of changing reasoning performance through prompts alone. With 8 CoT exemplars, the 540B model reached SOTA on GSM8K