Hello and thank you for reading. In this example, I am using a Constants file instead of the environment.ts because it's easier to understand for someone new. Yes, you should always use the .environement.ts. Also, I prefer to create and encode the url and the params by my self because I do not want my code to depend so much on the HttpClient module, in order to be safe for a future Angular update. Finally, the Core Module instead of the providedInRoot is common for the Angular 7 and in my opinion better because you have all the reusable services in one place.