A lathe works by locking in a long block of one of the above materials between a motor and a free-spinning pin at the other end. The motor spins the wood at high speed and using a bar called a "rest" the artist slowly and carefully presses a metal gouge into the spinning wood. At first, the main purpose is to round out the wood (yes this is how dowels are made). Then, once you have the desired roundness, the next step is to create your shape or contour using different types of gouges. Next you then move on to sand paper to smooth down the tool marks and make the surface soft and smooth, apply paint or stain and you're done.
Okay so that is just a simple description of turning a tubular shape, but a lathe as I mentioned before can also take big blocks of materials and not only turn the outside into a pleasing shape but also the inside, in the case of bowls and vases. I know in our forums I have seen a few talented artists create extremely small vases and bowls with amazing detail and finishes such as CDHM Artisan Bertie Pittman.