20.5. Including Files and Applets in JSP Documents
JSP has three main capabilities for including external pieces into a JSP document.
The include directive. The construct lets you insert JSP code into the main page before that main page is translated into a servlet. The included code can contain JSP constructs such as field definitions and content-type settings that affect the main page as a whole. This capability is discussed in the first following subsection.
The jsp:include action. Although reusing chunks of JSP code is a powerful capability, most times you would rather sacrifice a small amount of power for the convenience of being able to change the included documents without updating the main JSP page. The jsp:include action lets you include ...