Trivia Tuesday: What Are iPhone Stickers?

We've established that I'm often out of touch, one of the last people to adjust to new technology, and basically, unhip. (Unless it's hip to be square, and then I think I'm okay. If you don't understand this reference, go to Google and search for Huey Lewis and The News greatest hits.) Therefore, it's no surprise that I don't understand this iPhone stickers commercial that appears to air non-stop:



So do you send these stickers via messages/texts? If so, are these different than emojis? Can you only get these stickers with an iPhone7? And in the commercial, why does the guy slam a "Very Hungry Caterpillar" sticker in someone's food? That seems extremely rude and uncool. Unless of course, this is the in thing to do now.