During the process of throwing, the wheel rotates rapidly while the solid ball of
    soft clay is pressed, squeezed and pulled gently upwards and outwards into a hollow
    shape. The first step of pressing the rough ball of clay downward and inward into
    perfect rotational symmetry is called centring the clay which is a most important
    skill to master before the next steps: 
Opening (making a centred hollow into the solid ball of clay).
Flooring (making the flat or rounded bottom inside the pot).
Throwing or Pulling (drawing up and shaping the walls to an even thickness)
Trimming or turning (removing excess clay to refine the shape or  create a foot).
Considerable skill and experience are required to throw pots of an acceptable standard
    and, while the ware may have high artistic merit, the reproducibility of the method
    is poor. Because of its inherent limitations, throwing can only be used to create
    wares with radial symmetry on a vertical axis. These can then be altered by impressing,
    bulging, carving, fluting, and incising. In addition to the potter's hands these
    techniques can use tools, including paddles, anvils  and ribs,specifically for cutting
    or piercing such as knives, fluting tools and wires. Thrown pieces can be  modified
    to attach  handles, lids, feet and spouts.