I have a new site with about 20 pages. My eventual plan is to monetize with ads on each page. That means I need to set up the pages in such a way that will allow me, at a later time, to make a few changes that will affect all the pages.

From what I've been told, PHP will let me do that. I'm assuming it's similar to how you use a CSS file, something with which I am familiar. Before I add any more pages, I'd like to set up the code so that I will have everything in place.

Can I do this with PHP?