Rich cards are a new Search result format building on the success of rich snippets. Just like rich snippets, rich cards use schema.org structured markup to display content in an even more engaging and visual format, with a focus on providing a better mobile user experience.
Evolution of search results for queries like [peanut butter cookies recipe]: with rich cards, results are presented in carousels that are easy to browse by scrolling left and right. Carousels can contain cards all from the same site or from multiple sites.From Google Webmasters Blog
