Most people have been using the Internet long enough to expect certain things when they arrive at a website. Of course, these items may appear anywhere on a web page, but consistency is expected and although perhaps "boring" it will be appreciated by your site visitors.
Header - This is the title of your website, typically a business name and logo, but it can be anything that identifies your site other than its URL. Your header or masthead might also include an address, phone number, product specials or other information you find important enough to give prime visibility on your website.
Navigation - This is how people will get around on your site. You can provide multiple levels of navigation, but it is important to come up with a mental model of your site navigation before your site is built. And of course, it is critical to maintain consistency of navigation throughout your site.
Body - The body should provide the bulk content of each site page. It is the presentation of information, usually centrally located, and the primary reason you built your site in the first place. It is important to present this information cleanly and professionally because this is the content to which you are attracting your visitors.
Footer - Typically at the bottom of your web pages, the footer is the place to store "fine print" information like disclaimers and copyright directives. You can also use the footer to provide a link to your webmaster, your contact information, or your sitemap.
Of course, variability of sites across the Internet is what makes the web so interesting. And while most users appreciate creativity it's always important to provide useful information to your website visitors.