Okay, we don’t actually expect anyone to learn Adobe’s pen tool through the study of cubic Bézier curves — but we love this cool animation of how the Bézier spline is actually derived from the mathematical equations you control with your handy pen tool.
You can read more than you care to know about the mathematics that Postscript is based on — along with some more fascinating diagrams at Wikipedia:
Source: This tip inspired by last month’s Mastering Adobe’s Pen Tool mini-workshop led by Jason Hoppe.