How is ServletContext created?

WARNING: Stupid question alert. But I need to get my head around this.

"When the webapp gets loaded the container will create the ServletContext. There is only one ServletContext per webapp per JVM.

The ServletContext object is contained within the ServletConfig object which is provided by the web server upon servlet initialisation."

Therefore: 1. How is ServletContext created by the Container - if it is an interface? 2. If there is only one ServletContext per webapp and that is provided to ServletConfig (of which there is one per Servlet) then doesn't that mean there is one ServletContext per ServletConfig?