Unlike other processors, plugins play a central role in PostCSS—we can pick and choose what functionality we want to use; if it doesn't exist, then we are free to create our own version. Throughout the course of this chapter, we've covered some key concepts around the use of plugins, so let's take a moment to review what we have learnt.

We kicked off with a quick introduction to the use of plugins, which was swiftly followed by exploring the architecture of a standard plugin that included a look at some of the key files that make up a standard plugin. We then moved on to take a look at some of the classes, modules, and methods available as part of the API.

Next up, we began working through the construction of an example plugin, before constructing a suitable test process and correcting the errors generated from linting the code as part of the test. We then rounded off our plugin with a look in more detail, to understand some of the key concepts behind how it works.

Moving on, we then...