Matplotlib is one of the best Python plotting libraries that is able to produce publication-quality figures. Like Python, its aim is to make complex tasks simple. With over 7,550 stars (and counting) on GitHub, it is also one of the most popular open source projects. Its popularity directly translates into faster bug fixes, a friendly user community, and general usability. It takes a bit of time to learn the package, but it is well worth the effort.
In this section, we barely scratched the surface of Matplotlib. You'll find additional resources at http://matplotlib.org/2.0.0/index.html (the Matplotlib project page) and https://github.com/matplotlib/matplotlib (the Matplotlib GitHub repository).
In the coming section, we will take a look at another popular Python graph library: Pygal.