How can we change only inner part of a web page?

Question

I am developing a web application, where headers and footers for all pages are the same. What I want to achieve, is to change only the part of the page between the header an

Answer 1

create a div that contains the content, and give it a unique class or an id. Then in your jquery code bind a click event on the elements you want to use as navigation and in that bind use $("#div").load("page.php") or something like that to load content from another file into the div