More on footer.html: Where to source it?

From the blog template I can see the footer gets not sourced magically, so it has to be sourced explicitly in each page template, e.g. in entries.html, right?

Then the question is: Where to source it: Inside all <div>s (as I found in the blog template) or more outside, say, before the </html>? tag?

I'm not a big web expert, but I read somewhere JS code should be sourced as late as possible in an HTML document...

Thanks heaps for helping a template beginner!