The scope of a variable determines how long it will last and who can access it. Binding a variable to context scope will cause it to last the lifetime of the application and make it available to everyone. Binding it to session will make it available only to the user who owns the session and only for the length of that session. Request scope keeps a variable alive for one request/response cycle and allows it to be accessed by different components within that cycle. Page scoped values are gone as soon as context is moved to another resource.