Every Angular application has at least one component, the root component that connects a component hierarchy with the page DOM. Each component defines a class that contains application data and logic, and is associated with an HTML template that defines a view to be displayed in a target environment.
The @Component decorator identifies the class immediately below it as a component, and provides the template and related component-specific metadata.
Decorators are functions that modify JavaScript classes. Angular defines a number of such decorators that attach specific kinds of metadata to classes, so that it knows what those classes mean and how they should work.
