The master password unlocks your encrypted vault which grants you access to each of your passwords. Passwords managers help you generate unique and strong passwords, store them in one safe (encrypted) place, and use them while only needing to remember one master password. So, how do you manage the hundreds or even thousands of passwords you need to remember in your daily life? Remembering a lot of passwords is difficult, but security experts (including ISO) recommend that you DO NOT reuse passwords.
