The Core directory contains all the infrastructure functions that are always loaded. For example, in this directory, you might find the following resources: route guards, HTTP interceptors, layout components, routing error pages, infrastructure-level services like ThemeService, logging, AuthService, etc.
.
┣ core
| ┣ guards
| | ┗ singleton.guard.ts
| ┣ layout
| | ┗ toolbar
| | ┗ toolbar.component|.html|.scss|.ts
| ┣ pages
| | ┗ page-not-found
| | ┗ page-not-found.component|.html|.scss|.ts
| ┗ core.module.ts