If you are new to PowerShell, you may be worried about causing unwanted damage or change. One way of childproofing PowerShell is by changing the whatif-default like so:
$whatifpreference = $true
From now on, any cmdlet supporting the -whatif parameter will use it without you having to specify it. So any cmdlet that would change things on your system is effectively disabled. This affects anything that changes things, even creating a new folder is not allowed anymore:
Md c:\test
To override the default, you need to explicitly add this option: -whatif:$false
Md c:\test -whatif:$false