The Metal material is a simple way to create polished or rough metallic surfaces. It has a simplified UI where all you need to do is set the color and roughness. After that you're all done.
Choosing Color will tint the metal so you can have rich golds, cool silvers, or any metallic color you desire.
Adjust the Roughness slider to set the finish you want for your metal. Increase the value to add a more matte finish to your metal, or set it to 0 for perfectly polished surfaces. The slider goes up to 0.5, but you can type in a value up to one to create a even more dramatic matte finish.