When building a small web site, it is natural to think of it as a set of pages. As the site grows, however, this approach becomes problematic. Information that you want to show on several pages needs to be entered on each of those pages, so updates require making the same change multiple times, increasing the effort required and the chances for errors. Since the content and the HTML markup are intertwined, it is difficult for anyone to edit the content unless they have HTML skills.
There is a better way: store the site’s information in a database. Each page then is created from a template that provides the page structure, with content drawn from the database. This approach puts the information at the center of the site, rather than its presentation (the pages). It brings many powerful advantages over the static HTML approach:
Information architecture is a big topic. However you are building sites, it's essential to think deeply and clearly about how best to organize a site's content. If the site is a simple brochure site, then there may not be much to think about, but the more content a site has, the more important it is to invest effort in this area.