See the specification at https://html.spec.whatwg.org
<!DOCTYPE html>
<html lang="en">
<head>
<title>A basic HTML page</title>
</head>
<body>
<h1>A basic HTML page</h1>
</body>
</html>
See the specification at https://html.spec.whatwg.org/#the-meta-element
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="x-ua-compatible" content="IE=edge">
<meta name="author" content="">
<meta name="description" content="">
<meta name="keywords" content="">
<meta name="viewport" content="width=device-width, initial-scale=1">
</head>
</html>
See the specification at https://html.spec.whatwg.org/#the-style-element
<!DOCTYPE html>
<html lang="en">
<head>
<style>
h1 {
font-style: italic;
}
</style>
</head>
<body>
<h1>The HTML style element</h1>
</body>
</html>
See the specification at https://ogp.me
<!DOCTYPE html>
<html lang="en">
<head>
<meta property="og:title" content="The Open Graph protocol">
<meta property="og:type" content="website">
<meta property="og:image" content="">
<meta property="og:url" content="">
<meta property="og:description" content="">
</head>
</html>