LastPass is a zero-knowledge password manager that encrypts your vault locally before syncing across devices, ensuring only you can decrypt your credentials with your master password. It operates within the broader password management ecosystem, solving the problem of password reuse and weak credentials by generating, storing, and autofilling unique passwords for every account. A critical insight: LastPass uses PBKDF2-SHA256 with customizable iterations (default 600,000 for new accounts) to derive your encryption key—older accounts created before 2023 may have lower iteration counts (5,000 or 100,100) and should manually increase this setting in Account Settings > Show Advanced Settings > Password Iterations to improve security against brute-force attacks.