The code for plotting graphs is considered the frontend in Matplotlib's terminology. We first mentioned backends in Chapter 1, Introduction to Matplotlib, when we were talking about output formats. In reality, Matplotlib backends have much more differences than just support for graphical formats. Backends handle so many things behind the scenes! And that would determine the support of plotting capabilities. For example, the LaTeX text layout is supported only by Agg, PDF, PGF, and PS backends.