Notifications are the bread and butter of our Android experience. Something happens, we get a notification. It could be as urgent as a new email from our boss telling us that we missed a comma in a post (stuff like that has been known to happen when your boss is Artem) or as ordinary as a new Twitter mention or a shipping status change on an order or a new episode available of your favorite series. The difference between how you act on these notifications is huge. You can instantly tap to check a notification or, if you're on Android N, directly reply to it, you can dismiss it without a second look because it's not something you care about all that much, or you can leave it hanging in your notification shade as a reminder to check later.