This book covers Python mathematical library Num Py in detail. Num Py (short for Numerical Python) provides an efficient interface to store and operate on dense data buffers. In some ways, Num Py arrays are like Python’s built-in list type, but Num Py arrays provide much more efficient storage and data operations as the arrays grow larger in size. Num Py arrays form the core of nearly the entire ecosystem of data science tools in Python, so time spent learning to use Num Py effectively will be valuable no matter what aspect of data science interests you.