Bitmoji is an expressive cartoon avatar that can be linked to your Snapchat or used as a Sticker in the Apple Messenger app. You can download the Bitmoji app for free from the App Store, then use your device's camera to create an avatar that looks something like you. There is even a Bitmoji keyboard option for iOS, and tons of outfits for you to choose from. Once created, you can then use any of the Stickers from the huge Bitmoji library in most of the popular chat apps, including the payment app Venmo.
You can start fresh with your Bitmoji avatar by resetting it. Open Bitmoji and tap on the settings gear icon in the top left then scroll down and tap on "Reset Avatar."
You can unlink Bitmoji from Snapchat by tapping on your Bitmoji avatar in the top left, then "Edit Bitmoji." Then tap on "Unlink My Bitmoji" at the bottom.
You can change your Bitmoji avatar's clothes via Snapchat or the Bitmoji app. From Snapchat tap on your avatar in the top left, then tap "Edit Bitmoji" in the same spot, then "Change My Outfit."
Bitmoji is an app that allows you to create "your own personal emoji" and use it in a variety of messaging apps. Bitmoji was originally owned by Bitstrips, which was acquired by Snap Inc. (parent of Snapchat) in mid 2016. While it was quickly optimized and integrated with Snapchat, it can be used with other messaging apps, including iMessage. Here's how to install the Bitmoji keyboard on iPhone and use it in iMessage:
Adding the Bitmoji keyboard