There are some major upcoming changes in how Apple users will be accessing iCloud data through third-party apps.
Beginning June 15th and onwards, Apple users will need to acquire app-specific passwords for any third-party programs that wish to access iCloud data. This also means that they will need to activate enhanced password-authentication protocols if they want to keep using these apps.
Apple’s iCloud functions as a repository that syncs information between several different user devices, making sure that once a change has been made to one of the files, copies of all files across these devices are updated accordingly.
The purpose of app-specific passwords is to provide an additional layer of security. As in good practice these should be different than the Apple ID and its password, in the event of a data security breach, only the app-specific password will be stolen, while the Apple ID credentials will remain safe.
As of right now, however, Apple only requires app-specific passwords in cases when a user has decided to enable two-factor authentication. During this process, a user requires a password as well as a unique code to log in to the account.
When the new change is in full effect, using app-specific passwords will be mandatory, which also means users will be forced to use two-factor authentication.
According to the email that Apple Support sent to their user base, all users who link iCloud data to third-party apps will be automatically logged out when the change is pushed out. After generating an app-specific password for each program, they will be able to log in again.