[2019.06.23 study notes 3]
1. Define the Head html5 document, <head> element can be referenced in the footsteps tells the browser where to find style sheets
2 may be used in the <head> tag: <title> <meta> <link> <script> <script>
<! DOCTYPE HTML> <HTML lang = "EN"> <head> </ head> <-! Custom browser, search engine reads the contents -> <body> </ body> </ HTML>