Implicit variables are always available to JSTL - you don't need to set them before using them.

1. Page context: pageContext
   
   pageContext properties:
   

   Name	Type	Description
   page	javax.servlet.Servlet	The current servlet request
   request	javax.servlet.ServletRequest	The current servlet request
   response	javax.servlet.ServletResponse	The current servlet response
   servletConfig	javax.servlet.ServletConfig	The servlet config
   servletContext	javax.servlet.ServletContext	The application
   session	javax.servlet.http.HttpSession	The current HTTP session

   
   
   Note: request, response etc., is not directly available, you access them with pageContext.request, pageContext.response, etc.
   
   
2. Scope variables: pageScope, requestScope, sessionScope, applicationScope
   
   

   Name	Type	Description
   pageScope	java.util.Map	Name-value pair of page scoped variables
   requestScope	java.util.Map	Name-value pair of request scoped variables
   sessionScope	java.util.Map	Name-value pair of session scoped variables
   applicationScope	java.util.Map	Name-value pair of application scoped variables

   
   
   
3. Parameters, HTTP headers and cookies: param, paramValues, header, headerValues, cookie, initParam
   
   

   Name	Type	Description
   param	java.util.Map	Access to parameter values. Key is parameter name; value is the first value associated with the name.
   paramValues	java.util.Map	Access to parameter values. Key is parameter name; value is a list associated with the name
   header	java.util.Map	Access to header values. Key is header name; value is the first value associated with the name.
   headerValues	java.util.Map	Access to header values. Key is header name; value is a list associated with the name
   cookie	java.util.Map	Access to cookies. Key is cookie name; value is the value associated with the name
   initParam	java.util.Map	Access to application initialization parameters in web.xml.