Backend layer

This is the bottom-most layer where the graphs are displayed on to an output device. This can be any of the user interfaces that Matplotlib supports. There are two types of backends: user interface backends (for use in pygtk, wxpython, tkinter, qt4, or macosx, and so on, also referred to as interactive backends) and hard-copy backends to make image files (.png, .svg, .pdf, and .ps, also referred to as non-interactive backends). We will learn how to configure these backends in later Chapter 9, Developing Interactive Plots and Chapter 10, Embedding Plots in a Graphical User Interface.