Ans: This is a very popular interview question on JSP, which has been asked from a long time and still asked in the various interview. This question is good to test some fundamental concept like translation of JSP and difference between translation time and run time kind of concept.

Syntax for include Directive is <%@ include file="fileName" %> which means we are including some file to our JSP Page when we use include directive contents of included file will be added to calling JSP page at translation time means when the calling JSP is converted to servlet ,all the contents are added to that page .one important thing is that any JSP page is complied if we make any changes to that particular page but if we have changed the included file or JSP page the main calling JSP page will not execute again so the output will not be according to our expectation, this one is the main disadvantage of using the include directive that why it is mostly use to add static resources, like Header and footer .

Syntax for include action is < jsp:include page=”relativeURL” / > it’s a runtime procedure means the result of the JSP page which is mentioned in relative URL is appended to calling JSP at runtime on their response object at the location where we have used this tag

So any changes made to included page is being effected every time, this is the main advantage of this action but only relative URL we can use here ,because request and response object is passed between calling JSP and included JSP.