If you're already familiar with the Bezier formulation of curves, then you shouldn't feel overwhelmed by the topics presented here. If you're not, read the previous article "The Practical Guide to Bezier Curves".
This article is a primer for the next article in this series. The first 2 parts are intended to set up all of the math and definitions for B-splines, and Part 3 will discuss the algorithms and shortcuts. I believe this article and its companion to be essential to understanding a very common and powerful set of curves and surfaces.