The Anatomy of a Path
A path in Photoshop consists of several components:
First, a path has a segment; a path segment always has an anchor point at the beginning and end of it.
These anchor points determine the course of a path as it passes through the point. When you click with the Pen tool, successive clicks create anchor points with straight path segments in between anchors.
If you drag while you click, you create a curved path segment between where you are dragging and your previous click or drag. Also, when you drag while you're holding the mouse button, your finishing point is not an anchor point, but a different component of paths—the direction point.
A direction point is at both ends of a curved segment, sprouting off the last anchor point ...