While

Run a command block based on the results of a conditional test.

Syntax
      while (condition) {command_block}

Key

   condition      If this evaluates to TRUE the loop {command_block} runs.
                  when the loop has run once the condition is evaluated again

   command_block  Commands, separated by commas, to run each time the loop repeats.

As long as the condition remains true, PowerShell reruns the {command_block} section.

Examples

Count to 10:

 PS> while($val -ne 10) { $val++ ; Write-Host $val }

You can use carriage returns instead of semi-colons:

 PS> while($val -ne 10)
     {
       $val++
       Write-Host $val
     }

“A quarrel is quickly settled when deserted by one party; there is no battle unless there be two” ~ Lucius Annaeus Seneca

Related PowerShell Cmdlets:

Break statement
Continue statement
Do - Run a command block based on the results of a conditional test.
ForEach-Object - Loop for each object in the pipeline (foreach).
ForEach - Loop through values in the pipeline.
IF - Conditionally perform a command.
For - Loop through items that match a condition.
Switch - Multiple if statements.