2-Step provides an extra layer of security
Activating 2-Step Verification boosts protection of your account from hackers. We are all used to having one layer of security — our password — to protect our accounts. With 2-Step, if bad guys get through the password layer, they will still need your phone or other second verification method to get into your account.
Office 365 has 2-Step Verification built in, so once you’ve set it up on your account, all of your email and files within Office 365 will have that extra layer of protection.
The 2-Step Verification site has more information about this important feature for Office 365 and many more applications at UNC Chapel Hill.