Further reading
The TikZ manual includes some excellent tutorials in Part I, Tutorials and Guidelines. You can find the manual at https://texdoc.org/pkg/tikz in PDF format and https://tikz.dev/tutorials-guidelines.
Coordinates and coordinate systems are explained in depth in Part III, Section 13, Specifying Coordinates, and online at https://tikz.dev/tikz-coordinates.
The geometric shapes we learned to draw in this chapter are called path operations in the TikZ manual. Part III, Section 14, Syntax for Path Specifications, is the reference for them. You can read that section online at https://tikz.dev/tikz-paths.
