How Do I Add in an ID for the a href tag

New rather simple question im afraid.

I want to put in <a href="">link</a> and in the href tag i want to put in the ID of a page, so that IF i change the url (friendly urls) it will update automatically (after clearing cache).

Just wondering how i can write this into my templates?

Regards
André

once again, further reading and playing has fixed this one! for anyone in need, its very simple: <a href="[~ID_OF_PAGE~]">link</a>

André