This week, we had two different Googlers answer questions about link placement on a web page and how it differs having links in your main body content versus links in your footer, header, boilerplate content, etc.
Zineb from Google answered it on Twitter on January 25th in French saying:
je laisserai faire l'algo. Les liens sitewide en footer ou en header n'ont pas un tres grand poids en general.
I let do the algo. The sitewide header and footer links are not a very great weight in general.
So sitewide header and footer links seem to be given less weight by Google, which is common sense to most of you out there.
Does it matter if the main content area contains lots of links to external domains and few links to other pages on the same domain? Does it degrade the quality of that page?
So I think there are two aspects there, on the one hand this is the area of the page where you have your primary content, the content that this page is actually about, not the menu, the sidebar, the footer, the header...
Then that is something that we do take into account and we do try to use those links.
The other thing to keep in mind is you still need to make sure that within your site you have a clear linking structure. That can happen if you have a clear set up with a side bar, menu...
But if you don’t have a clear linking structure, then we pick up just a bunch of links to external sites, then what might happen is we can’t really crawl the rest of your site properly because we can’t discover it properly.
He goes on a bit more, so you can listen to the whole thing: