Question: i see a lot of web site that.. remember when i return without using registration. 
I think they save cookies or something... 
So i'm asking you: in asp.net / vb.net how can i save the id of a user ? 
What are the command to do this ? 
Thanks in advance...

Answer: 
You need to [use cookies](http://msdn.microsoft.com/en-us/library/ms178194.aspx).
SLaks is correct - use cookies. The [Login](http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.login.aspx) control has this functionality built in.