Creating Reusable Service in Angular | Update Angular 9 to Angular 10 | In Hindi

How can we update an existing Angular 9 application to Angular 10. What is service. How we create a service. Command for Creating Service : ng g s userInfo. What is HTTP Client Module what is HTTP Client . How to read from the local file in case of Static website and how to read from the server. What is the purpose of creating a service.