ASP.NET controls automatically keep their data
when page is sent to the server in response to
events (like a user clicking a button).
this persistence of data is called view state

in asp.net application there may be different
server errors like file not found,server error,
etc.when those errors happens default ASP.NET error
page is shown which looks odd and users don't
understand what type of errors occured.to overcome
these problems it's a good idea to use own
error files.

you can put application specific settings in the
appSettings section of your app.config file in your
c# windows form application.you can access,edit,update
those settings.I show you how -

Gravatar.com is used to store one's avatar image according to email.
then if you comment in any application using your that email address
where gravatar image has been programmed then your avatar image will
be displayed in the application.