Welcome to this addition of the PowerShell ABC's where you'll find 26 posts detailing a component of the PowerShell scripting language, one letter at a time. Today's letter is the letter "C". For "C" I've picked the most efficient type type of commands supported by PowerShel, the CmdLet.
CmdLets (pronounced "Command-let"), functions, scripts, and native Win32 executables are the four types of commands supported in PowerShell. A Cmdlet is implemented by a .NET class that derives from the Cmdlet base class in the PowerShell SDK. This class is compiled into a DLL and loaded into the PowerShell process. Since a Cmdlet is native code loaded in process, it's the most efficient of the four types of commands to execute.
Cmdlet's have the names in the form of Verb-Noun, where the verb specifies the action you are performing and the Noun refers to the object you are performing the action on. Cmdlet's are very similar to builtin commands in many common command shells.