Opera’s signature "Speed Dial" start page is a great way to organize your favorite sites. Without an account, you lose these if you reinstall Windows or switch computers. With a login, they are backed up to the cloud instantly.

The Opera browser client receives a session token from Opera’s own sync server, cryptographically bound to the Google-provided email. The user is now logged into Opera Sync without ever typing a password into Opera.

Privacy purists often reject this feature because it ties a unique identifier (Google email) to a specific browser installation. For maximum anonymity, users should create a dedicated, pseudonymous Opera account using a throwaway email—but that sacrifices convenience.