Two factor authentication

Two-step verification adds an extra layer of protection to your account. Whenever you sign in to an important website or link a new device, you’ll need to enter both your password and also a security code sent to your mobile phone.

Requirement: In order for two-step verification to work correctly, you’ll need a mobile device capable of receiving text messages or running a compatible mobile authenticator app.

Mobile app

If you choose to receive your security codes through an authenticator app, you’ll first need to download one. The authenticator app you choose will need to generate a unique time-sensitive security code. Most authenticator apps can generate security codes even when cellular/data service is not available, which can be useful when traveling or where coverage is unreliable. Any app that supports the Time-based One-Time Password (TOTP) protocol should work, including:

Google Authenticator (Android/iPhone) Duo Mobile (Android/iPhone) Authenticator (Windows Phone 7)