Bootstrap/_includes/social.html

<!-- Meta -->
<meta name="description" content="{{ site.description }}">
<meta name="author" content="{{ site.authors }}">

<!-- Twitter -->
<meta name="twitter:site" content="@{{ site.twitter }}">
<meta name="twitter:creator" content="@{{ site.twitter }}">

{% if page.title %}
  <meta name="twitter:card" content="summary">
  <meta name="twitter:title" content="{{ page.title }}">
  <meta name="twitter:description" content="{{ page.description }}">
  <meta name="twitter:image" content="{{ site.url }}{{ site.social_logo_path }}">
{% else %}
  <meta name="twitter:card" content="summary_large_image">
  <meta name="twitter:title" content="{{ site.title }}">
  <meta name="twitter:description" content="{{ site.description }}">
  <meta name="twitter:image" content="{{ site.url }}{{ site.social_image_path }}">
{% endif %}

<!-- Facebook -->
{% if page.title %}
  <meta property="og:url" content="{{ site.url }}{{ page.url }}">
  <meta property="og:title" content="{{ page.title }}">
  <meta property="og:description" content="{{ page.description }}">
  <meta property="og:type" content="website">
{% else %}
  <meta property="og:url" content="{{ site.url }}">
  <meta property="og:title" content="{{ site.title }}">
  <meta property="og:description" content="{{ site.description }}">
{% endif %}
<meta property="og:image" content="{{ site.url | replace: 'https://', 'http://' }}{{ site.social_image_path }}">
<meta property="og:image:secure_url" content="{{ site.url }}{{ site.social_image_path }}">
<meta property="og:image:type" content="image/png">
<meta property="og:image:width" content="1200">
<meta property="og:image:height" content="630">