The volute is the decorative turnout at the base of a staircase. In this image the seam where the two joined handrail pieces meet is called the up ramp.
Volutes spiral to the right or to the left of the staircase depending on the placement of the baluster.
The volute is an extravagant gesture adding character to an otherwise linear staircase.
The spiral of the volute can be simple, or it can be exaggerated, as with this amazing piece of woodwork. When the handrail ends with a single turn, the detail is called a turnout.
Under this volute the curtail is visible. The curtail is the curved staircase tread that extends beyond the first step at the outside of the baluster.
The vertical rod that's more robust than the surrounding spindles is called the volute newel, and it supports the volute at its center.
Another option for a staircase landing is to just use a large newel post, which is located at the beginning of the baluster and forgoes any spiraled woodwork.
Some newel posts have curved decorative elements adorning them, like this ball finial.
Here a newel post and a volute are combined.