https://techcrunch.com/2017/10/17/google-launches-strongest-security-opt-in-program-for-high-risk-users/

Google has today launched a free, opt-in program aimed at users who believe their Google accounts — such as Gmail, Drive, YouTube etc — to be at particularly high risk of targeted online attacks.

The Advanced Protection program currently consists of the three main elements: defending Gmail and Google account users against phishing attacks by requiring 2FA via a token generated by a hardware security key; locking down the risk of malicious applications grabbing sensitive data by automatically limiting full access to Gmail and Drive to just Google apps (for now); and reducing the risk of hackers gaining access to a Gmail account via impersonation by adding more steps to the account recovery process.