CAPTCHA - Wikipedia
https://en.wikipedia.org/wiki/CAPTCHA
A CAPTCHA is a type of challenge-response test used in computing to determine whether or not the user is human. The term was coined in 2003 by Luis von Ahn, Manuel Blum, Nicholas J. Hopper...
2Captcha: reCaptcha Solving Service, Online Captcha Recognition...
https://2captcha.com/
2Captcha is a human-powered image and CAPTCHA recognition service. Use API to send your Solve Captcha. Starting from 0.5 USD for 1000 solved CAPTCHAs. API available for most popular...
The Official CAPTCHA Site
http://captcha.net/
CAPTCHA: Telling Humans and Computers Apart Automatically. A CAPTCHA is a program that protects The term CAPTCHA (for Completely Automated Public Turing Test To Tell Computers and...
What Does CAPTCHA Mean? | CAPTCHA Types & Examples | Imperva
https://www.imperva.com/learn/application-security/what-is-captcha/
What is CAPTCHA. CAPTCHA stands for the Completely Automated Public Turing test to tell Computers and Humans Apart. CAPTCHAs are tools you can use to differentiate between real users...
reCAPTCHA is a security service that protects your websites from fraud...
https://www.google.com/recaptcha/about/
reCAPTCHA is a security service that protects your websites from fraud and abuse.