Cross Domain Cookie Provider

I've been working on some sort of authentication and authorization module recently. I use .Net encrypted cookie, copied from a MSDN article, but I found the authentication cookie can't go across different applications. Then I try to create the cookie on my own. This time, it works, but it still doesn't work across doamin. Therefore, I googled "cross domain cookie" and reached this article. I've been hearing stuff about single sign-on, things like server and token. This design pattern seems to be similar to what I heard before.