The ServletContext interface , defines methods , which can be used by a web application , in order to interact with the servlet container . A servlet container can pass initialization parameters , to a web application , by using what is called : context parameters.

The ServletConfig interface , defines methods , which can be used to retrieve initialization parameters , passed to a specific servlet , by the servlet container catalina , when creating the servlet and calling its init method .

The config object , is an instance of ServletConfig . It is an implicit object , which is not necessary to declare , and which can be used inside a JSP page . A JSP page is converted , to a servlet .