Snapchat acquired Bitstrips, the company responsible for those comic strips with your avatar that did the rounds briefly on Facebook, back in March and is finally putting that purchase to good use.
You can now download the Bitmoji app, which will then let you link it to your Snapchat account and fire out cartoon versions of yourself in snaps to friends and followers. You can also use these Bitmoji stickers in chats, which should be more interesting than the simple emoji.
If the person that you're sending a message to has already created a cartoon avatar of themselves you'll be able to use theirs too. This will allow you to send a more personal and customised sticker to someone.
You can see how it all works in the introductory video below.