This week I learned that a Modal is a pop up window that you can use methods through. Annotations are only metadata set on the class using the Reflect Metadata library. Decorator corresponds to a function that is called on the class. Decorator are used for creating an attribute annotations that stores array. Decorator is a function that gets the object that needs to be decorated. The main building blocks for Angular are modules, components, templates, metadata, data binding, directives, services, and dependency injection.