Twitter announced today that it has open sourced Twemoji, a set of 872 emoji characters. This means that emoji characters tweeted from phones will now be visible on the web and will look the same across all platforms. Twitter also partnered with Automattic to bring emoji to WordPress.com, and users can start adding emoji to posts right away.
Adding emoji to content is fairly easy and intuitive when done from a mobile device. On desktop, you might need a cheat sheet. Mac users can type Command + Control + Space while in a text editor. Windows 8+ users can make use of the touch keyboard, which includes emoji support.
Twitter’s announcement is major advance for emoji users worldwide, given that inconsistent emoji display across platforms has long been a sore issue.
The Jetpack team is already busy adding emoji support so that self-hosted sites can also utilize them. However, any plugin developer can create a plugin that adds Twemoji to WordPress using the Twemoji API. If you have a self-hosted WordPress site and don’t use Jetpack, the WP Emoji One plugin is another option for adding emoji support to your site.
Plugin devs should keep in mind that you can only store emojis in the database on MySQL 5.5 and above, unless you use workarounds like encoding them with base64
See http://pento.net/2014/04/07/wordpress-and-utf-8/ and https://core.trac.wordpress.org/ticket/27961 for more details.