How to Enable Two-Step Verification for Your Apple ID
Using two-step verification is completely optional — you’re not required to use the extra security measure if you don’t want to. For those who opt-in, Apple gives fair warning that you’ll need your trusted device with you to access your account information. Apple does provide a printable Recovery Key in case you lose your iOS device or forget your password, but they won’t be able to help you if you lose it. I recommend storing the Recovery Key in 1Password for safe keeping. If you do lose the Recovery Key, you can generate and print a new key if you can log into your account.
This is an important step in making Apple IDs more secure. I just finished enabling two-step verification on mine and putting my recovery key into 1Password.