On my site I all the webpages contain the exact same XHTML code and some css for a menu.

Can someone please tell me is it possible to have an external HTML page with the code and a link?

The way I mean is like linking a webpage to an external css stylesheet.

This means that the page would open quicker and make the webpages a smaller file size and to save having all the same code on each webpage.

All help much appreciated