CLR vs Runtime vs Host

Here http://msdn.microsoft.com/en-us/library/zaf1h1h5(v=VS.90).aspx it says:

In the .NET Framework version 2.0, the CLR provides hosting management interfaces to control many features of the hosted runtime, enables the host application to implement other management interfaces provided by the runtime, and lets you implement your own hosting management interfaces.

For purposes of discovery, the management interfaces fall into two broad categories:

Management interfaces that thehostimplements and theruntimediscovers through the IHostControl interface.

Management interfaces that theCLRprovides and the host discov开发者_开发知识库ers through the ICLRControl interface.

Can you pls explain what these bold words are?

Thanks.

CLR is the Common Language Runtime, the environment under which all the dotnet applications run.
Host (in this context) is the unmanged application which hosts the CLR under it so that managed code can be run in its context (for eg. SQL Server, IIS etc). The parent page of the link provided by you explains this.

"Runtime" rerers to CLR.

Update
Have a look at this MSDNMag article for a detailed overview of CLR hosting APIs