why do you use html { in css code example

Example 1: CSS IN HTML

<!-- Styles can be inserted in html using <style></style> element -->
<style>
	body {
    	background-color: cyan/*Color*/; 
  	}
</style>

<!--CSS can also be linked using link tag in html 
-the link tag is a self-closing tag-->

<link rel="stylesheet" type="text/css" href="filename.css"/>

Example 2: how to use css

<link rel="stylesheet" href="stylesheet.css">
<div class="mydiv"></div>
<style>
.mydiv {
background-color: /*Color*/;
color: /*Another color*/;
}
</style>