Bootstrap pemula

Bisa jelasin mastah apa itu role="presentation",,udah cari digugel gak nemu". Terima Kasih

<div class="container">
		<h1>Hiyaahiyaa</h1>
		<br/>
		<ul class="nav nav-pills">
			<li class="active"><a href="https:/sekolahkoding.com">Home</a></li>
			<li role="presentation"><a href="#">Menu 1</a></li>
			<li><a href="#">Menu 2</a></li>
			<li><a href="#">Menu 3</a></li>
		</ul>
	</div>