The Shape tool
Segments
A segment is the portion of a curve that lies between two nodes. A curve object can have two types of segments: curved or straight. You can bend a curved segment by dragging it with the Shape tool; when you move its nodes, the curve will change shape. A straight segment will never bend, regardless of the position of its nodes.
Nodes
When you select a curve object with the Shape tool, all of that object's nodes are displayed. You can shape a curve object by moving a node or by moving the control points that appear when you select a node.
Control points determine the curve of a segment as it passes through a node. You can control the curve of a segment by varying the control point's angle and its distance from the node. A node at the end of a path has one control point, and a node in the middle has two control points. However, because straight segments don't bend, a node at the end of a straight segment won't have a control point for that segment.
Tips
You must select a node or a segment before you can manipulate it or change
its properties. Selected nodes become highlighted in one of two ways: hollow, if
the associated segment is a straight segment; solid, if the segment is curved.
Before you can select a node or a segment, you must select a curve object
with the Shape tool.
How to
To shape a curve object
Related topics
Drawing basic shapes