A cmdlet (pronounced “command-let”) is a lightweight Windows PowerShell script that performs a single function. A cmdlet, which is expressed as a verb-noun pair, has a .ps1 extension.
Windows PowerShell has over two hundred basic core cmdlets and had been extended to 1000’s due to administrators writing their own.
Each cmdlet will have a help file that can be accessed by typing Get-Help “cmdlet name”. All this and more are in PowerShell so have a look.
More info on PowerShell can be found here: http://technet.microsoft.com/en-us/library/bb978526.aspx