Twitter cards show additional information associated with a link. Twitter draws this information from meta tags on your page. Twitter cards support the open graph protocol, so there are only two additional lines of code you would need to add to your site via my meta open graph script to support a basic summary card:
<meta "twitter:card" type="summary" /> <meta "twitter:site" type="@kishner" />
If you want to incorporate the above meta tags, use the following updated
add meta og script.
Make sure you replace @kishner with your own Twitter handle.
In addition to having the meta tags on your page, you need to get your site whitelisted by Twitter. After you've published a post with the meta tags, enter your URL in the Card Validator. If the card is valid but your site has not been approved, then submit for review. After your site has been approved, your Twitter cards will show up.