<meta charset='utf-8'>

<!-- title -->
<title>...</title>
<meta property='og:title'  content='...'>
<meta name='twitter:title' content='...'>

<!-- url -->
<meta property='og:url'  content='http://...'>
<meta name='twitter:url' content='http://...'>
<link rel='canonical'       href='http://...'>

<!-- desc -->
<meta name='description'         content='...'>
<meta property='og:description'  content='...'>
<meta name='twitter:description' content='...'>

<!-- image -->
<meta property="og:image"  content="http://...">
<meta name="twitter:image" content="http://...">

<!-- ua -->
<meta http-equiv='X-UA-Compatible' content='IE=edge,chrome=1'>

<!-- viewport -->
<meta name='viewport' content='width=device-width'>
<meta name='viewport' content='width=1024'>

More opengraph

<meta property="og:site_name" content="...">
<meta property="og:type" content="website">

<meta property="fb:app_id" content="...">
<meta property="fb:admins" content="UID1,UID2"> <!-- unless there's app_id -->

<meta property="og:audio" content="http://.../theme.mp3">
<meta property="og:video" content="http://.../trailer.swf">

Opengraph for articles

article:published_time
article:modified_time
article:expiration_time
article:author
article:section
article:tag

Apple-only

<meta name='format-detection' content='telephone=no'>

Progressive web apps

Add to homescreen

<meta name='mobile-web-app-capable' content='yes'>
<meta name='apple-mobile-web-app-capable' content='yes'>
<meta name='apple-mobile-web-app-status-bar-style' content='black'> <!-- black | black-translucent | default -->

Theme color

<meta name='theme-color' content='#ff00ff'>

Manifest

<link rel='manifest' href='/manifest.json'>

Icons

<!-- Minimal -->
<link rel='icon' type='image/png' href='[email protected]'>
<link rel='icon' sizes='192x192' href='[email protected]'>
<link rel='apple-touch-icon' href='[email protected]2.png'>
<meta name='msapplication-square310x310logo' content='[email protected]'>

<!-- Apple -->
<link rel='apple-touch-icon' href='touch-icon-iphone.png'>
<link rel='apple-touch-icon' sizes='76x76' href='touch-icon-ipad.png'>
<link rel='apple-touch-icon' sizes='120x120' href='touch-icon-iphone-retina.png'>
<link rel='apple-touch-icon' sizes='152x152' href='touch-icon-ipad-retina.png'>

<!-- Microsoft -->
<meta name='msapplication-square70x70logo' content='icon_smalltile.png'>
<meta name='msapplication-square150x150logo' content='icon_mediumtile.png'>
<meta name='msapplication-wide310x150logo' content='icon_widetile.png'>

Chrome on Android recommends 192x192.

Reference