I've read a lot of information about duplicate content across web pages and was interested in finding out about how that affected the header and footer of a website. A lot of my pages have a good amount of content, but there are some shorter articles on my website.  Since my website has a header, footer, and sidebar that are static, could that hurt my ranking? My only concern is that sometimes there's more content in the header/footer/sidebar than the article itself since I have an extensive amount of navigation. Is there a way to define to Google what the header and footer is so that they don't consider it to be duplicate content?