What is the verification code of Douluo Mainland?

The verification code is a public automatic program, which is used to distinguish whether the user is a computer or a person. The verification code question is generated and judged by the computer, and only human beings can answer it, which can prevent malicious password cracking, ticket brushing, forum flooding and other problems. It can be divided into Gif animation verification code, mobile phone short message verification code, mobile phone voice verification code and video verification code. Because the verification code is generated randomly, there is a great chance that there will be an unrecognizable verification code picture. There are usually hints. Click the current captcha image directly to complete the replacement of captcha. Generally, you must enter the verification code in the place where the user ID is registered and in major forums. Common verification codes are four digits or letters, and six digits are also common.