Ejemplo de cabecera

<head>
 <title>TODO supply a title</title>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">

 <!--Bootstrap (incluye jquery)
 -->
 <link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
 <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
 <script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>

 <!-- jquery UI (incluye js y tema)
 -->
 <link rel="stylesheet" href="https://ajax.googleapis.com/ajax/libs/jqueryui/1.11.4/themes/redmond/jquery-ui.css">
 <script src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.11.4/jquery-ui.min.js"></script>

 <!-- mis estilos y mi js
 -->
 <link href="estilos.css" rel="stylesheet" type="text/css"/>
 <script src="codigo.js" type="text/javascript"></script>

 </head>