A web page that is being renders consists of a lot of things like logo, text, pictures, hyperlinks, navigation structure, etc. HTML5 offers a set of markup elements that allow you to create a structured layout for web pages. These pages are often referred to as Semantic Markup.
Semantic Markup expresses its meaning an purpose to the developers and the browser developers. This article will cover semantic markup elements of HTML5 which can be used to properly layout web pages. Unlike the conventional <div> element, symantic elemens are used for specific purposes. These elements are <header>,<nav>,<section>,<footer>, <article>, and <aside>.
Read the rest of the tutorial here: http://www.developer.com/lang/understanding-the-proper-way-to-lay-out-a-page-with-html5.html