I heard twitter captha But I don't know what is it? So plz can anyone tell me what is it.
CAPTCHA is an acronym for "Completely Automatic Public Turing Test to Tell Computers and Humans Apart". It is a task, that human can easily solve, but computer not. It is intended to determine whether or not the user is human. Usually, CAPTCHA requires that the user type the letters and digits of a noised and distorted image.
The most common CAPTCHA is to require that the person enter a password. As they are the only person who knows what their password is this not only distinguishes between them and computers but also distinguishes between them and other people.You then only need some other type of CAPTCHA to prevent computers signing up to be able to use their own password.
The term CAPTCHA is stand for "Completely Automatic Public Turing Test to Tell Computers & Humans Apart". This is a program that can generate & grade tests that human can pass but computer cannot. CAPTCHA code generally contains letters & digits of distorted images.
There are several places you can get CAPTCHA free online, wordpress is one of them. It really is helpful to ensure that you have genuine human beings responding/inquiring on your site. I'd encourage you to use one of the available options if you have a site that seems to have a lot of computer generated mail coming to it.
I agree with the above.
CAPTCHA is often used to foil bots from auto-submitting data as well.