Design account security architecture, plan the core system design for identity authentication, session management, and account protection; Counter complex security threats, identify and defend against risks such as credential stuffing, phishing, simulated login, brute force cracking, etc., and build a multi-layered protection system including multi-factor authentication, device fingerprinting, risk control engine, etc. Here, there are global business scenarios, challenges posed by hundreds of millions of users, and cutting-edge identity authentication technologies.