In the past year, apps like Snapchat and Facebook Messenger have helped popularize stickers, at least in the west. Asian messaging services like Line have been on board for some time and sell branded packs from popular franchises like Hello Kitty. It's logical to assume that, like custom emoji, Twitter will seek to monetize its graphics and allow brands to pay cold hard cash to add their own.
If you've been looking to up your sticker game, or just think your dog could use a nice pair of cartoon sunglasses, Twitter will now place a small smiley icon on the bottom-right part of a photo you wish to attach. Once you hit the button, you'll be presented with a menu of available stickers that are loosely grouped by category, allowing you to select, quickly place and post to your followers.