Proper semantic markup
Use special HTML5 tags: <article>, <aside>, <header>, <footer>, <menu>, <section> Bad: <div id="header"> <div id="logo"> <h1><a href="/">My blog</a></h1> </div> <div id="description"> <h2>About my blog</h2> </div> </div> Good: <header> <h1> <a href="/">My blog</a> </h1> <h2>About my blog</h2> </header>