Ejemplo:

      <section>
      <h1>Forest elephants</h1>
      <section>
      <h1>Introduction</h1>
      <p>In this section, 
      we discuss the lesser known
      forest elephants.
      </section>
       <section>
      <h1>Habitat</h1>
      <p>Forest elephants do
      not live in 
      trees but among them.
      </section>
      <aside>
      <p>advertising block
      </aside>
      </section>
      <footer>
      <p>(c) 2010 The Example  company
      </footer>