Add or remove a point on a path
You can modify the points and segments on a path during and after creating the path. For a quick reference of modifications that you can make to a path, see Direct Selection tool modifier keys and Pen tool modifier keys.
In the Tools panel, click Selection , and then select that path you want to add a point to.
In the Tools panel again, click Pen.
While hovering over the path, the pen tool will change to to indicate that you can add a point. Click to add a point.
If you add a point to a curved segment, the resulting point will have the appropriate control handles defined to describe the tangent of the curve at the position of that point. Alternatively, if a point is added to a straight segment, no control handles will be defined.
Select the path objects between which you want to draw lines. (To select multiple objects, hold the CTRL key).
In the Tools panel, click Pen .
While hovering over one of the open end points, the pen tool will change to to indicate that you can extend the current path. Click and optionally drag on the end point. The line segment attached to that point becomes highlighted. At this point, you can optionally add additional points before you join this path to another path.
While hovering over one of the other open end points, the pen tool will change to to indicate that you are going to connect the points with a line, or the pen tool will change to to indicate that you are going to close the path. Click and optionally drag on the end point.
Dragging defines the control handle of the point, which describes the tangent of the line at that point. The shape of the curve can be modified after the path is drawn by changing the angle and length of the control handles for that point. For more information, see Change the shape of a curve and Redefine control handles for a point on a path.