Glossary
Review the definitions for terms used across Cloudflare's Turnstile documentation.
| Term | Definition |
| CAPTCHA | A CAPTCHA test is designed to determine if an online user is really a human and not a bot. CAPTCHA is an acronym that stands for "Completely Automated Public Turing test to tell Computers and Humans Apart." |
| secret key | The secret key allows communication between your application backend and the Cloudflare Turnstile server to validate the widget response. |
| sitekey | The sitekey is used to invoke Turnstile on your site. |