Two-step authentication provides an extra layer of security for signing into Google accounts. It requires users to enter their password as usual, and then receive a code via text, voice call, or mobile app to enter. This adds something the user has, like their phone, beyond just a password. Users can choose to not use two-step verification on trusted computers for simpler sign-ins. However, it will still be required on new devices to better protect the account in case of hacked passwords.