There is a nice blog from Andy Harjanto on InfoCard System so do not want to explan here the basic concepts. He has done a great job describing with some sample code all the elements of InfoCard system.
I was recently playing with the Avalon and Indigo BETA SDK to see the InfoCard systems in action. There is something which may be confusing (seems like today I am going to talk only about confusions :) ) to some people. With Indigo comes a Windows service called Microsoft Digital Identity service (InfoCard system) which displays a GUI where you could create sets of attributes. These sets are called “Cards”. Lot of people will take this to be “InfoCards”.
An InfoCard is just a metadata which says what is the authentication mechanism to be used at STS .. what are supported claims at STS etc. It does not contain the data or attributes about user.
Microsoft InfoCard 1.0 Beta 1 GUI displays digital identities of user and not the Info cards. Wish there is a better word MSFT can use for these set of attributes instead of “Cards” to avoid possible confusion.
Now this also raises a question, the GUI from Digital Identities service is for selecting a set of attributes not info cards (if my understanding is correct) so will there be a selection mechanism for InfoCards also ?.... A use case can be imagined in which I have 2 InfoCards (for eg 2 authentication mechanisms) for the same relying party then client on my PC should know of a way to select the correct InfoCard.