Really clear introduction to Sharepoint architecture

I think I understand Sharepoint, but to be honest I don't know what I don't know.

A link to some clear documentation would be helpful, or short of that, descriptions of what the following are:

• A Web Application
• A managed path
• A site collection
• A site

When would I use each, and how do they all relate to each other?

I've looked at Microsoft's discussion of Information Architecture, but it doesn't join the dots.

Solution 1:

My favorite one is this:
http://blogs.technet.com/wbaer/archive/2007/07/10/understanding-hierarchy-and-basic-concepts-of-navigation-in-microsoft-office-sharepoint-server-2007-windows-sharepoint-services.aspx

But some people find that a little too technical. I have also used the following in the past:
http://sharepointkb.wordpress.com/2008/08/20/sharepoint-terminology/
http://blogs.msdn.com/skelley/archive/2007/06/24/sharepoint-terminology-defined.aspx
https://sharepoint.missouri.edu/wiki/Wiki%20Pages/SharePoint%20Terminology.aspx

Solution 2:

I have difficulty with this one all the time. I find that because these things exist for underlying technical reasons and not for Information Architecture reasons it is not possible to explain them in those terms adequately.

Even with reletively non technical users I have some success explaining these things in terms of the technical limitations/reasons for thier existence rather trying to map to any Information Architecture entities.