Tags that Define EL Variables
An EL variable is an attribute of the JSP page context. A variable can be added using the JSTL <c:set> action, or the setAttribute() method of the instance variable called pageContext that points to the javax.servlet.jsp.PageContext object of the Web page. The setAttribute() method takes the following parameters:
The name of the scripting variable. This name is used to refer to the variable on the Web page.
The object reference to the variable to be added to the page.
The scope of the variable can be one of the following constants defined in PageContext:
PAGE_SCOPE Available until the current page processing completes (this is the default)
REQUEST_SCOPE Available until the current request completes allowing the variable ...