# reCAPTCHA **Domain:** Human-machine classification **Doc Type:** Developed System Node **Maturity:** Developed **Collection:** [[collections/Gamification|Gamification Collection]] ## Definition **reCAPTCHA** is Google's service for distinguishing legitimate human interaction from automated abuse. Earlier versions used explicit challenges; reCAPTCHA v3 can assess interaction without a challenge and return a score that a site uses to choose an action. ## Significance reCAPTCHA is a familiar micro-tournament over identity: behavior is observed, a human/bot likelihood is inferred, and access changes. It shows how gamelike tasks can perform unpaid classification and how invisible scoring moves adjudication behind the interface. ## Sources - Google for Developers, [reCAPTCHA](https://developers.google.com/recaptcha) - Google, [Choosing a reCAPTCHA version](https://developers.google.com/recaptcha/docs/versions) ## Routes [[wiki/Topics API|Topics API]] · [[wiki/Cost Matrix|Cost Matrix]] · [[wiki/False Positive|False Positive]]