Home → Multi Factor Authentication Help (MFA) → Turn on 2-step (MFA) Verification in Gmail → Gmail Turn on 2-Step Verification

2.1. Gmail Turn on 2-Step Verification

Turning On MFA and Adding Multiple Authentication Devices (Cell Phones, etc.): https://support.google.com/accounts/answer/185839?hl=en&co=GENIE.Platform%3DiOS&sjid=338363818572518639-NA

(While it is not required to use more than one key or device as a second form of authentication, it is recommended to add your Android or iPhone as another way (backup method) to achieve Two Factor Authentication in case you lose your YubiKey).