Grammar
1. Use two spaces instead of tabs (tab)-This is the only way to ensure consistent presentation in all environments.
2, nested elements should be indented one time (that is, two spaces).
3, for the definition of attributes, the property value ensures that all are double-cited (avoid using single quotes).
4, do not add a slash behind the auto-closing element--HTML5 The specification explicitly stated that this is optional.
5. Do not omit the optional end tag.
Instance:
<! DOCTYPE html>
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 "/>
<meta http-equiv= "x-ua-compatible" content= "Ie=edge"/>
<meta name= "viewport" content= "width=device-width,initial-scale=1.0"/>
<!--[If Lt IE 9]>
<script src= "Http://apps.bdimg.com/libs/html5shiv/3.7/html5shiv.min.js" ></script>
<script src= "Http://apps.bdimg.com/libs/respond.js/1.4.2/respond.js" ></script>
<! [endif]-->
<title></title>
<meta charset= "Utf-8"/>
<link rel= "stylesheet" href= "Bootstrap-3.3.5/dist/css/bootstrap.min.css"/>
<body>
<H2 class= "Help-block" >hello bootstrap<script src= "Jquery/jquery-2.1.4.js" ></script>
<script src= "Bootstrap-3.3.5/dist/js/bootstrap.min.js" ></script>
</body>
Bootstrap HTML Encoding Specification