Polishing is the process of creating a smooth and shiny surface by using rubbing or a chemical action.
In metallography polishing is used to create a flat, defect free surface for examination of a metal's microstructure under a microscope. Silicon based polishing pads or diamond solution can be used in the polishing process.
There are three generally used terms used by many in the jewelry and metal polishing industry that are often used interchangeably. It's not important which terms you use, but I present them for your information. The terms are deburring, polishing and buffing. The generally accepted definitions are:

1. Deburring is the removal of all sharp edges, air bubbles and burrs on a piece.
2. Polishing is the use of abrasives to get general surface finish improvement.
3. Buffing is the step to get a smooth, bright, high luster final finish.

To apply the compound to the wheel, tear down the cardboard tube and hold the exposed compound against the wheel for about 2 seconds. You'll see how the wheel takes on the color of the compound. You'll also notice how the wheel turns black almost immediately when you start to buff. This black build-up is not harmful to the wheel or the part being buffed. Rake the wheel if you notice excessive metallic build-up or at the start of the day to prevent scratching the surface.
As you progress from one compound to the next finer grit remember to clean any residue hot water and detergent.