for Google
<meta name="description" content="" />
<meta name="keywords" content="" />
<meta name="author" content="" />
<meta name="copyright" content="" />
<meta name="application-name" content="" />
for Facebook.
Link debug : https://developers.facebook.com/tools/debug/
<meta property="og:title" content="" />
<meta property="og:type" content="article" />
<meta property="og:image" content="" />
<meta property="og:url" content="" />
<meta property="og:description" content="" />
for Twitter
<meta name="twitter:card" content="summary" />
<meta name="twitter:title" content="" />
<meta name="twitter:description" content="" />
<meta name="twitter:image" content="" />