Redo-Cmdlets, Contact Cmdlets

I am studying some office 365 commands and am a little confused by the Redo* Commands.

Redo-MsolProvisionUser

Redo-MsolProvisionContact

Redo-MsolProvisionGroup

When are those commands used, and how do you know when to use them? Next how do you create a simple contact using powershell? I do not see an new-msolcontact cmdlet.

thanks,

Robert

Robert