How to Use -confirm in PowerShell

-Confirm is a switch in most PowerShell cmdlets that forces the cmdlet to ask for user confirmation. What you're actually looking for is the Read-Host cmdlet:

$confirmation = Read-Host "Are you Sure You Want To Proceed:"
if ($confirmation -eq 'y') {
    # proceed
}

or the PromptForChoice() method of the host user interface:

$title    = 'something'
$question = 'Are you sure you want to proceed?'

$choices = New-Object Collections.ObjectModel.Collection[Management.Automation.Host.ChoiceDescription]
$choices.Add((New-Object Management.Automation.Host.ChoiceDescription -ArgumentList '&Yes'))
$choices.Add((New-Object Management.Automation.Host.ChoiceDescription -ArgumentList '&No'))

$decision = $Host.UI.PromptForChoice($title, $question, $choices, 1)
if ($decision -eq 0) {
    Write-Host 'confirmed'
} else {
    Write-Host 'cancelled'
}

Edit:

As M-pixel pointed out in the comments the code could be simplified further, because the choices can be passed as a simple string array.

$title    = 'something'
$question = 'Are you sure you want to proceed?'
$choices  = '&Yes', '&No'

$decision = $Host.UI.PromptForChoice($title, $question, $choices, 1)
if ($decision -eq 0) {
    Write-Host 'confirmed'
} else {
    Write-Host 'cancelled'
}

This is a simple loop that keeps prompting unless the user selects 'y' or 'n'

$confirmation = Read-Host "Ready? [y/n]"
while($confirmation -ne "y")
{
    if ($confirmation -eq 'n') {exit}
    $confirmation = Read-Host "Ready? [y/n]"
}