Running applications in production can be very complex. A lot of things might happen when your application is in the wild, things that you don't expect, or that slipped your QA process, such as edge cases or events in the data center that affect your application. Besides these cases, there are times when you want to investigate the correct flow of work and get insights about how a certain feature is used, or if it is used at all. Your best friend in the aforementioned cases is the log. Logging in ASP.NET Core is now a first-class citizen, and a logging framework, middleware, and abstraction layer are included out-of-the-box, so it's much easier to work with different logging packages and providers.
The Microsoft.Extensions.Logging package, which is referenced by the Microsoft.AspNetCore.App meta-package, contains...
