Under:
System Preferences > Users & Groups > Advanced Options > Aliases:
There are 2 lines. One is my Apple ID. The second is in the form
com.apple.idms.GUID
What is the significance of these fields?
I do not have my Apple ID set to login my computer.
Best Answer
A user name alias functions as a simple way to create a shorthand version of an account name.
For example, if a users full account name is “Buscar웃SD” (which would be difficult to type every time to log in), one could setup an alias as “BSD” and just login with the shortened version instead.