About Windows authorization.

Windows authorization has always been confusing. After reading Microsoft's Windows License, it is still confusing. In the blog Park, Windows is widely used for development, so I would like to ask you. The problem is as follows:

1. I remember that when I installed windows, I asked if the license was calculated by server or by connection. What are the differences between the two types? If the number of connections is allowed, what is the number of connections?
2 If IIS is used and the operating system is Windows2003, does the number of IIS connections have anything to do with the Windows License? How many restrictions are imposed on the number of IIS connections? Do you need to purchase additional licenses?

I did not understand this problem yesterday. Please express it to someone else.
(I can't understand Microsoft's official language. Thank you first .)