Cloudflare Turnstile is a client-side JavaScript library that integrates into web pages to provide a non-intrusive bot detection and mitigation service. When loaded, it runs a series of non-interactive JavaScript challenges in the background to verify that a user is human, without requiring them to solve a puzzle or identify objects. This script collects data related to the browser environment, user behavior, and other signals to distinguish legitimate users from automated bots. It aims to minimize user friction while providing robust protection against various forms of automated abuse, such as spam submissions, credential stuffing, and data scraping. The script injects an invisible challenge into a form or page, which then communicates with Cloudflare's backend to validate the user.