In ASP.NET, Global.asax acts as the entry point for your APPLICATION.
In ASP.net Core,startup.cs is the entry point for your application.
In Startup.cs file
The constructor loads the AppSettings.json file using ConfigurationBuilder class
The ConfigureServices() method adds the SERVICESREQUIRED by the application. For example, here you add MVC and Entity Framework to the services COLLECTION.
The Configure() method specifies and configures the services added EARLIER for application’s use.