Let's begin our introduction with a look at the anatomy of a matplotlib plot in the following figure:

Matplotlib uses a hierarchy of objects to display all of its plotting items in the output. This hierarchy is key to understanding everything about matplotlib. The Figure and Axes objects are the two main components of the hierarchy. The Figure object is at the top of the hierarchy. It is the container for everything that will be plotted. Contained within the Figure is one or more Axes object(s). The Axes is the primary object that you will interact with when using matplotlib and can be more commonly thought of as the actual plotting surface. The Axes contains the x/y axis, points, lines, markers, labels, legends, and any other useful item that is plotted.

A very clear distinction needs to be made between an Axes object and an axis. They are completely separate objects. An Axes object, using matplotlib terminology, is not the plural of axis but instead, as mentioned earlier, the object that creates and controls most of the useful plotting elements. An axis simply refers to the x or y (or even z) axis of a plot.

All of these useful plotting elements created by an Axes object are called artists. Even the Figure and the Axes objects themselves are artists. This distinction for artists won't be critical to this recipe but will be useful when doing more advanced matplotlib plotting and especially when reading through the documentation.