Content: meta tags

meta tags and Metadata Guidelines (W3 EOWG)

meta elements from Harvard University:

<meta property="twitter:account_id" content="1491443782" />
<meta name="twitter:site" content="@harvard">
<meta name="twitter:creator" content="@harvard">
<meta name="twitter:card" content="summary_large_image">

<meta property="og:site_name" content="Harvard University"/>
<meta property="og:type" content="university"/>
<meta property="og:title" content="Harvard University"/>
<meta property="og:url"
  content="https://www.harvard.edu"/>
<meta property="og:description" content="Harvard University is devoted to excellence in
teaching, learning, and research, and to developing leaders
in many disciplines who make a difference globally.
Harvard University is made up of 11 principal academic units."/>
<meta property="og:image"
  content="https://www.harvard.edu/sites/default/files/default_images/harvard-social1200.jpg"/>