What is the ReAct pattern in prompt engineering?

ReAct, short for Reasoning and Acting, is a prompting pattern that interleaves chain-of-thought reasoning with tool actions. The model produces a Thought explaining what to do, an Action calling a tool, an Observation receiving the tool's result, then another Thought, and so on until it reaches a final answer. ReAct was introduced by Yao and colleagues in 2022.