What is captcha? and how to write a captcha code ?

What is captcha?  What is Captcha – The full name of CAPTCHA is “Completely Automated Public Turing test to tell Computers and Humans Apart”.  CAPTCHAs are a tool you can use to differentiate between real users and automated users, such as bots.  CAPTCHAs provide challenges that are difficult for computers but relatively easy for humans. … Read more