Have you ever been in the middle of writing a text message and scrolled through the selection only to find that the one you need to use doesn't exist? If you have a great idea for a new emoji, the Unicode Consortium is currently open to submissions.
How to send in your own design or idea, and what the application entails are included in this section.
Even if they don't pop up on your phone, a lot of them already exist. You should do some homework before you create more work for yourself.
Check to see if your idea has been approved. If not, check to see if someone has already submitted the same idea, and it is currently under review.
The page that tells you which designs have been approved and which ones have been declined is helpful when putting together your application. Check out the selection factors for exclusion and the criteria for consideration.