Official Description: Core library to enable emoji compatibility in Kitkat and newer devices to avoid the empty emoji characters.

CommonsWare’s Notes

This library, and the others in androidx.emoji, exist to try to offer a continuously-updated set of emoji for apps to use. Otherwise, you wind up with device-supplied emoji from device-supplied fonts, and they may not cover newer emoji.

This specific library offers widgets, like EmojiEditText, for working with Google-supplied sources of emoji.

Most of the material on emoji compatibility is on the former Android Support Library packages. The artifacts and imports are different, but much of the functionality should be the same.