In my web application I got Header.jsp file which contains default header contents. Im including it in all other pages using jsp:include tag inside body tag of each individual p
Good response @Gwenc37. You can have any tags in any other tags, but it is always best to keep to the W3C standards and specifications. Later on in the project you might get to a point where your HTML does not parse correctly in a browser or even worse breaks.
To be safe, rather keep to the W3C standards. This way you cannot go wrong. Hope this helps.