The include tag lets you include other JSP files in your portlet’s JSP, theme, or web content. This can increase readability as well as provide separation of concerns for JSP files.
The page attribute is required and specifies the path to the JSP or JSPF to
include. The servletContext refers to the request context that the included
JSP should use. Passing <%= application %> to this attribute lets the included
JSP use the same request object as other objects that might be set in the
prior JSP.
Below is an example configuration for the <liferay-util:include> tag:
<liferay-util:include
page="/relative/path/to/file.jsp"
servletContext="<%= application %>"
/>
Now you know how to use the <liferay-util:include> tag to include other JSPs
in your portlets, themes, and web content.