How to keep HTML5 working in older browsers?

Question

Browsers

Tell me the code or add-on to support older browsers HTML5

Answer 1

Modernizr ?

Answer 2

<!--[if lte IE 8]>
Выкиньте свой старый ослик и купите новый!
<![endif]-->

Answer 3

For donkey

<!--[if lt IE 9]>
      <script src="https://oss.maxcdn.com/html5shiv/3.7.3/html5shiv.min.js"></script>
      <script src="https://oss.maxcdn.com/respond/1.4.2/respond.min.js"></script>
    <![endif]-->