index.html:
<html>
<head>
<title>CSS Overview</title>
<link rel="stylesheet" type="text/css" href="styles.css">
</head>
<body>
<h1>Hello, world!</h1>
<p>This is my HTML page.</p>
<div class="non_unique_div_class">Div1</div>
<div class="non_unique_div_class">Div2</div>
<div class="non_unique_div_class">Div3</div>
</body>
</html>
Notice the above HTML. The class is shared between three elements. If we want to apply a style to all three of those, we can use the class. We use the dot (.) to select a class, instead of the hash (#) which we would use to select an ID.
style.css:
.non_unique_div_class {
background: blue;
color: white;
}