Why do you need a verification code to distinguish a computer from a real person? What is its principle?

Nowadays, many websites need to use verification codes for registration and login. Their purpose is to distinguish computers from real people. ?

The literal translation of verification code is the Turing test that automatically distinguishes computers from humans. Turing test is actually a very famous experiment in artificial intelligence, and its principle is as follows: the experimenter can't tell the difference between a machine and a person by asking them some questions.

But if the experimenter can't tell the difference between them, the verification code is the reverse and variant of this Turing test, and its purpose is to distinguish between a computer and a real human, which is what.

Before this product appeared, it was because when the Internet was not developed, spam was everywhere, and some people posted a lot of spam advertisements by registering a large number of new accounts.

However, the programmer's current technology finds it difficult to identify the handwritten things accurately, so the verification code comes into being.

It can effectively avoid the threat of bankruptcy caused by violence. On the basis of graphic verification code, it has gradually evolved new ways such as slider verification code, image verification code and smart verification code.

But now our main verification codes are sent by SMS, which is more convenient and quick, and it also greatly reduces the time for people to identify verification codes.

In this way, to a certain extent, the situation that your account is leaked and your identity is forged by computer software can be avoided. Because of its own limitations, computer programs can't tell whether the captcha input is human or software, but with the development of technology, their recognition degree will be higher and higher, and machines will gradually have the ability to recognize and understand captcha. Therefore, in order to interfere with the recognition ability of the machine, we can deliberately add some image noise in it, so that the script on the page can further assist in judging whether this is the behavior of human operation or the behavior of machine operation, which can greatly reduce the leakage of our account.

This is the essence of captcha. When the Internet first appeared, the limited contact made them unable to accurately identify many image problems.