After registering for a Xiaomi account, you can gain access to MiCloud, MiCredits, and other Xiaomi services. To ensure your account security throughout the registration process, we ask that you provide some personal information, including mobile number and email address. Please choose either your phone or email address to bind. This is used mainly to retrieve or edit your MiPassport password and protect account security:
Phone number is one of the easiest and most reliable method to protect your account. Because your phone is portable, so even if you forget your password, you can use a relatively simple method to regain access to your account. Additionally, we can utilize your phone number to further verify and prevent abnormal activities.
Email address is a good option for long-term usage as it is not easy to lose or change. Provide this address to help protect your account security and retrieve your password and helps to send news about Xiaomi services. Additionally, we can utilize your email address to further verify and prevent abnormal activities.
Related question:- What is MiPassport setting and what are its uses?