What is Kestrel (vs IIS / Express)

Question

What is the kestrel web server and how does it relate to IIS / IIS Express?

I come from developing apps on IIS Express and hosting them on an IIS web server. With AS

Answer 1

1. Multiple apps on the same port is not supported in Kestrel.
2. Windows Authentication does not exist on Kestrel.
3. Request Filtering is much more fully featured in IIS.
4. Mime Type Mapping is much better in IIS.
5. HTTP access logs aren’t collected in Kestrel.