When people talk about throwing pottery, they generally mean the process from the time the clay touches the wheel to the time the wheel is stopped. In this more general (and most commonly used) sense, throwing is the entire activity of shaping the clay on the potter’s wheel.
One part of the general activity of throwing is a specific step called throwing. To throw the clay means to bend it between your finger joints. The right finger is lower than the left. This is important since the discrepancy is what forces the clay to bend.
As the potter’s hands move upward, the clay is stretched through the bend, with the excess clay being forced upward. This creates the pot’s height as well as thinning the walls