In one of controllers in my Grails application I'm preserving a parameter value in a session variable like this: session.myVariable = params.myValue After that, I can access the saved value from different controllers/GSP-pages as long as I actively use the app. However, if I don't use my app for a while, even though my browser window is still open, the session variable looses it's value. Does this happens because the session expires? I was under impression that a session lives until the browser window is still open, but apparently I was wrong. What should I do to ensure all session variables I define in my Grails app don't expire until the browser is closed? Is there any way to set session timeout manually? Thank you in advance for your answers!