Google declared that they will add carousel based search results at the snippet level. This means that when the user searches for something and Google feels content from that source is warranted, then instead of showing more search results listed below, it will show a carousel box below that the user may slide through.
Here is an animated GIF of how it works on mobile device:
Google quoted, "When you search for a topic, just scroll down to see a "carousel" of recent articles, videos or more on that subject. Tap any link to read or watch exactly what you’re interested in."
However the question arises that how does one get their site to show on this snippet carousel? Google added some tips on Google+ saying that one can add Articles rich snippets to "help" their "algorithm select the proper images or titles for their carousel results."
Google did add that it doesn't give users a better shot of showing up in the carousel but if they do qualify, it helps them figure out which images to add. Google said:
“Note that this markup is purely advisory – Our system use a variety of signals to determine which content to display in SERPs. Just like with Rich Snippets, we do not guarantee showing content you marked up.”Google Adds Carousel Based Search Results At Snippet Level!,