Just as objects can be transformed, the nodes of curves and shapes can be transformed too.
Node transformation works by forming a selection box around selected nodes. In doing so the box can be transformed in the same way that an object's selection box can be. As a result, the position of nodes relative to each other is altered in the transformation process which reshapes the curve or shape in different ways.
To transform multiple nodes:
With the Node Tool, select one or more nodes on a curve or shape.
On the context toolbar, enable Transform Mode in the Transform section.
Resize, rotate and skew either directly on the curve or shape using selection box handles or use the Transform panel for absolute precision.
To transform shapes for a simple distortion effect:
Select two nodes on the shape.
Enter Transform Mode.
With the pressed, drag any selected node inwards or outwards.
This is particularly effective on simple shapes such as rectangles.