The Pen tool
The Pen tool 
lets you build
Bezier paths by placing a
series of anchor points (sometimes called "nodes") and control handles (or "tangent handles").
Each segment on the path consists of the two anchor points on either side of
the path segment and the two control handles 
. Both the lengths and directions of the control
handles affect the shape of a Bezier curve.
A curve point on a Bezier path has visible control handles. A corner point has control handles that are fully retracted to the same position as the anchor point itself (so you can't see them). A cusp point has either one control handle fully retracted or has two control handles, but they act independently of each other. For more information about turning one type of point into another, see Corners vs. curves.
Curve point (top), corner point (middle), and cusp point (bottom)
Once you have the Pen tool selected in the Toolbox, you can start creating anchor points by performing one of these actions:
- To create a corner point click anywhere in the workspace.
- To create a curve anchor point with visible tangent handles, click and drag.
- To create a cusp point with the "in" handle retracted fully and the "out" handle extended, position the cursor by pressing CTRL+ALT while you drag the cursor.
- To create a cusp point with the two control handles extended but acting independently of each other, drag the cursor to create in and out handles, and then go back and press the ALT key while dragging the cursor on the out handle you just created.
For all anchor points except the starting point, you can hold down the SHIFT key while clicking or dragging to constrain the new anchor point or its handles to a 45- or 90-degree angle from the previous anchor point. (The actual angle is determined by the Rotation steps setting in the Units and Grids panel of the Options dialog box .)
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Tip: You can remove the last anchor point you added by pressing the DELETE or Backspace key. |
To end the path (stop drawing), do one of the following:
- To create a closed path, position the cursor on top of the first anchor point (the starting point) and click or click and drag. If you click, that anchor point will be a cusp point with a fully retracted "in" handle. If you drag, the point will be a curve or a cusp (depending on the status of its "out" handle).
- You can double-click at any point to place an ending anchor point, which is a corner point.
- You can press the ENTER key to end the path at the last-placed anchor point.
As you draw, you will not be able to see the path from the previous anchor point to the anchor point you're about to create until you actually click or click and drag.
Appending paths
When the Drawing tools append to path option is selected in the Stroke panel of the Options dialog box, you can easily extend an already-existing path with the Pen tool by placing the cursor over the beginning or end point of the line and then drawing. Or, you can draw a new path with the Pen tool and position the cursor over one of the open nodes of a path as you release the mouse button. In this case, the new path will be joined with the old one.
Adding and removing points
When you have the Pen tool selected and you place the cursor over an anchor point in a selected path, the cursor temporarily changes to the Delete Anchor Point tool. If you click, it will remove that point from the path. Similarly, if you place the Pen tool over a segment of a selected path, it temporarily changes to the Add Anchor Point tool, and clicking will add a point at that position. For more information, see Adding and removing anchor points.