What does the check code mean?

1.CAPTCHA is a public * * * fully automatic program, which is used to distinguish whether users are computers or people. Generally, you need to enter important information when registering or entering it. Universal verification code can prevent malicious password cracking, ticket brushing and forum flooding, and effectively prevent a hacker from constantly trying to log in to a specific registered user by using a specific program brute force cracking method;

2. At present, verification code is a popular way for many websites, and we have also realized this function in a relatively simple way. This question can be generated and judged by computers, but only humans can answer it. Because the computer can't answer the question of the verification code, the user who answers the question can be considered as human.

3. At present, there are mainly the following types of verification codes: 1, gif verification codes that can be randomly transformed; 2. Send the SMS verification code to the designated mobile phone number; 3. Voice verification code for voice broadcast; 4. The verification code composed of random numbers, letters and Chinese is dynamically embedded in videos in MP4, flv and other formats; 5. There is also a verification code presented as a picture.