What are the purposes of these two modules?
import { BrowserModule } from \'@angular/platform-browser\';
import { platformBrowserDynamic } from \'@angular/platfo
platformBrowserDynamic is a function used to bootstrap an Angular application.
CommonModule is a module that provides all kinds of services and directives one usually wants to use in an Angular2 application like ngIf. CommonModule is platform-independent.
BrowserModule exports CommonModule and provides a few services specific to the browser platform (in contrary to ServerModule or ServiceWorkerModule).
BrowserModule should only be imported in AppModule, CommonModule can be imported everywhere.