What is the use of CAPTCHAS?

[yuva12]

CAPTCHA or Completely Automated Public Turing test to Tell Computers and Humans Apart is a technique to distinguish between humans and computers. CAPTCHA is mainly used as a security check to ensure only human users can pass through. Generally, computers or bots are not capable of solving a captcha.

[beingnaive]

Captcha is a tool that is used to ensure that there is a human accessing that page, where captcha is used. There are many benefits of sing captcha and use cases may easily vary, depending on the requirements of a specific page.
Most commonly used with forms. For instance, if you want to ensure that a genuine user is submitting the form, then you can use captcha.
Captcha can be of different types, and the most popular one is by google that may ask you to click a check box or identify certain images. People also generate captcha on their own which usually is a text written on an image, that robots can’t read but humans can.
The user input for captcha verification is then validated before posting the form.