A matplotlib.axes.Axes class is central to the matplotlib API because it defines the plotting area where data is drawn.
An Axes object has two (or sometimes three?) matplotlib.axis.Axis (or more specifically matplotlib.axis.XAxis and matplotlib.axis.YAxis) objects representing the x,y coordinates.
It's possible to attach more Axis objects to display additional data.
Like a Figure, an Axes object has a Patch which determines the shape, background and border of the plotting region.
This patch is a Rectangle for cartesian, a Circle for polar coordinates.
Current Axes
In order to support pylab/pyplot state machine, a figure has a current Axes.
The current Axes can be set or gotten with the Figure methods sca() and gca().