A massive data breach has exposed 16 billion login credentials from platforms like Apple, Facebook, and Google, making it one of the largest leaks in history. Cybersecurity experts warn that hackers could use this data for credential-stuffing attacks, where stolen emails and passwords are tested across multiple sites. The leak, dubbed "RockYou2024," contains credentials from past breaches but remains a severe threat due to widespread password reuse. Users are urged to enable two-factor authentication (2FA), change passwords immediately, and avoid reusing them across services. Password managers and checking breach databases (like HaveIBeenPwned) are recommended for protection.