# ReAct

> An agent pattern that interleaves reasoning and acting: the model thinks, takes a tool action, observes the result, and reasons again — looping to a goal.

_The Agentic Web Lexicon · /glossary/react-pattern · [JSON](/api/glossary/react-pattern) · [all The Agentic Web Lexicon](/glossary)_

- **term:** ReAct
- **category:** core
- **short_def:** An agent pattern that interleaves reasoning and acting: the model thinks, takes a tool action, observes the result, and reasons again — looping to a goal.
- **long_def:** ReAct (Reason + Act) combines chain-of-thought with tool use so an agent alternates 'thought' and 'action' steps: it reasons about what to do, calls a tool, reads the observation, and updates its plan. It is the canonical loop most tool-using agents implement.
- **see_also:** agentic-loop, tool-use, chain-of-thought
- **etymology_origin:** — (verify-against-primary-at-build)
- **related_to:** agentic-loop, tool-use, chain-of-thought, ai-agent
- **contrast_with:** Unlike plain chain-of-thought, which only reasons, ReAct also acts between reasoning steps — grounding each thought in a real observation from a tool.
- **example:** A ReAct agent answering a live question reasons ('I need current data'), calls a search tool, reads the result, then reasons again before answering.
- **source:** https://arxiv.org/abs/2210.03629
- **status:** active
- **why_it_matters:** ReAct is the loop the agentic web is built to serve: every markdown twin, JSON API and callable tool is an 'action' an agent takes between reasoning steps.
- **sameAs:** https://arxiv.org/abs/2210.03629
- **bridge_entity:** agentic-loop
- **last_verified:** 2026-07-06
- **md_twin:** /glossary/react-pattern.md