Master Password is a completely new way of thinking about passwords.
The standard secure approach to handling passwords and pass phrases is by generating these secrets randomly and storing them in a vault. Unfortunately, this is an extremely dangerous and fragile approach which decouples you from your own identity. You've created a hardware or trust and availability dependency that sits between you and your services.
Master Password liberates you from this. There is no vault. No secret file or data. No externals to trust. Your identity is now your master password, a memorable phrase. To access your services, the Master Password algorithm acts as a secure calculator, deriving your service-specific key from your identity on-demand.
You can literally lose everything you own as a result of a natural disaster, legal action or accident today; all you need to regain access to your services tomorrow is your master password and a Master Password calculator.