两步/双表单登录（非双因素认证）：名称及优势问询

1) What's the exclusive name for this login method? #

This step-by-step login flow is most commonly referred to as Progressive Login (you might also hear it called Stepwise Login or Multi-Step Login in some contexts). The key difference from traditional single-form login is that it splits credential collection into sequential, separate submissions—first verifying the user’s identity via username/email, then prompting for the password (and even extra verification steps if needed later).

2) What are the core advantages of using this technique? #

Here’s why this pattern has grown in popularity over the past year:

• Blocks username enumeration attacks: By only submitting the username/email first, you can design the system to return identical feedback (e.g., "If this account exists, we’ve sent login instructions to your inbox") no matter if the account is valid. This stops attackers from scraping lists of real accounts to target with brute-force password attempts.
• Boosts user experience: Splitting the form into smaller steps reduces cognitive load—users don’t feel overwhelmed by a long list of fields upfront. It also makes account recovery smoother: if someone forgets their username, you can confirm the account exists first before guiding them through reset steps, instead of making them re-enter all credentials after a failed submission.
• Easily extends to multi-factor authentication (MFA): This flow naturally fits adding extra security layers. After the password step, you can seamlessly prompt for a 2FA code, security question, or biometric check without cluttering a single initial form.
• Cuts down on submission errors: With each step focusing on one input, users can fix mistakes (like a typo in their email) right away, instead of having to re-enter all their info after a failed single-form attempt.

内容的提问来源于stack exchange，提问作者summsel