If you open up the components folder, you should see a bunch of subfolders. Each subfolder is either a component, or a collection of components.

A collection of components could be nodes, taxonomy-terms, etc. Your structure could then look like this:

my-theme
_sass-essentials
components
_global
node
status-messages
YAML Created with Sketch.
my-theme.info.yml
YAML Created with Sketch.
my-theme.libraries.yml
my-theme.theme

We will cover in later chapters what to put in these folder.

General theming we have to do in the _global folder. The global theming is a component too. This might look odd at first, but it means that the global component is a component we will load in, on each page.