Color - Gradient in Inkscape
Gradients are defined in terms of Stops.
A Stop has:
in the Gradient.
The default Gradient has two Stops, both with the same color but with different transparencies.
You can add as many stop as you want.
There are two ways to add a gradient:
Once a gradient line has been created, you can add a stop by:
Select the object and click on:
Color: Both the Fill and Stroke paint tabs will show the color of the Stop and can be used to change the color.
Fill and Stroke dialog after selecting the object: