► ConfigureServices method is optional and defined inside startup class.
► It takes care of registering services that are consumed across the application using Dependency Injection (DI) or Application Services.
► It's get called by host before 'Configure' method to configure the app's services.
► Configure method is used to add middleware components to IApplication Builder instance that's available in Configure method.
► It accepts IApplication Builder as a parameter and also it has two optional parameters: IHostingEnvironment and ILoggerFactory.
► Using this method, we can configure built-in middleware such as routing, authentication, session, etc. as well as third-party middleware.
► Configure method also specify how the app respond to HTTP request and response.