Concept is very similar to global variables and local variables in C / C .
JSP has four ranges, Page, Request, Session, Application.
Page nodules the range of JSP Page in a single page;
The scope of the request is only between a JSP page, and then this property is invalidated;
The Session range is the time when the user and the server is connected, and the user has failed to disconnect the attribute;
The Application range is the largest, cautious, and execute the service to the server until the server is started. It may cause the server to load too heavy.
If you don't have any examples, what example I have written.
