Are @@variables in a Ruby on Rails controller specific to the users session, or are all users going to see the same value? <p>I have a controller in which there is a "viewless" action. That controller is used to set a variable called <code>@@ComputedData={}</code>. But the data is computed based on a csv file a user of the application uploaded. Now are users going to see their specific data or will the <code>@@ComputeData</code> be the same for all users? Could someone explain me this concept? I'm really shaky on it. Thank you in advance and sorry for the noob question. </p>