Simply put, this book provides the best explanation of the gradient, the divergence, and the curl in any book I've seen.  It really should be a required reference/text for every physics and engineering program in the country.  All the mathematics is here, but the author also lucidly explains in words and diagrams the physical meaning of these three operations.  Many students learn how to manipulate these operations, but they often have trouble understanding exactly what they mean.  This book is easy to read (how many textbooks can you say that about?) and there are lots of problems to illustrate key points after each chapter.  The author uses the mathematical formalism to solve some basic problems in electrostatics to provide real-world examples.  After working through this book, you'll not only be able to calculate the curl of a vector function, you'll know exactly what it means.