Question: Do you know what Twitter Cards are? Twitter is well-known by now, of course, but Twitter Cards aren’t. Twitter Cards are what meta tags are for Google and what Open Graph tags are for Facebook. Twitter says Twitter Cards enable marketers to “attach media experiences to Tweets that link to your content.” All it takes is the addition of a few lines of HTML to your Web pages; users who tweet links to your content will have a “card” added to the tweet, which will be visible to their followers. There are plenty of Twitter Card tags to choose from, including summary cards, photo cards and media player cards. Twitter lays out a list of rules for the use of Twitter Cards, which marketers should read before trying them out. (Marketing Land)