Page Heirarchies & Stuctures
More than that, though, each page of your site has to be directly connected to each other. Imagine each of your pages connected by little lines, something like this:
See how it's starting to look more like a spider's web rather than a traditional kind of hierarchial structure? They call it the World Wide Web for a reason. More than that, though, this kind of structure increases the chances that every page in your site gets indexed by seacrh engine spiders that get on your little "web" there, looking for content.
It's a lot like linking to a site from your site: when you link to another site that you think your users/customers might find useful, you are, in effect, creating a spider's thread from your page to the resource, not only for spiders to follow, but for your users, too. It works conversely, too: when you've got great content that people link to, they create a thread from their page to yours, increasing your relevance to Google, in particular, thus helping your SEO.
To break it down: your index page should link to every other section of your site, and so should every other page in the site. A page without links to the other sections of your site or with only one way into it is pretty useless for both your customers and for search engine spiders (though I'm sure there are arguments for "orphaned" or "semi-orphaned" pages like that, though I can't imagine what they are).
In our next few installments, we'll discuss how to built a functional navigation system for your site that won't hurt its SEO (no Java or scripts?!?!), and effectively using linking to keep your social networks up-to-date and relevant.