<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<!------ Include the above in your HEAD tag ---------->
<!-- Include in Header (Ignore if already included) -->
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<!-- Include in body -->
<div class="dropdown">
<a class="dropdown-toggle" data-toggle="dropdown">Dropdown Example
<span class="caret"></span></a>
<ul class="dropdown-menu">
<li><a href="#">Option 1</a></li>
<li><a href="#">Option 2</a></li>
<li><a href="#">Option 3</a></li>
</ul>
</div>
