The code for plotting graphs is considered the frontend in Matplotlib terminology. We first mentioned backends in Chapter 1, Hello Plotting World!, when we were talking about output formats. In reality, Matplotlib backends differ much more than just in the support of graphical formats. Backends handle so many things behind the scenes! And that determines the support for plotting capabilities. For example, LaTeX text layout is only supported by AGG, PDF, PGF, and PS backends.
We have been using non-interactive backends so far, which include AGG, Cairo, GDK, PDF, PGF, PS, and SVG. Most of these backends work without extra dependencies, yet Cairo and GDK would require the Cairo graphics library or GIMP Drawing Kit, respectively, to work.
Non-interactive backends can be further classified into two groups--vector and raster. Vector graphics describe images in terms of points, paths, and shapes that are calculated using mathematical formulas. A vector graphic will always...