Have you ever spent hours amending a menu structure manually throughout a website, having to amend each page one by one. Well theres a very easy way to use a simple PHP function to display the contents of a file, wherever you want on a website. So for example - your navigation, you can have this in a single file, and call it to display on every page, and when you want to add or amend a link, you just edit the one file and it will cascade down to all other pages.