Twemoji 2.4 makes a number of changes to Emoji 5.0 additions to bring these more in line with other vendors.
Twitter Twemoji emoji images are displayed on the Twitter.com website and TweetDeck. Twitter apps for Mac, iPhone, iPad and Android use emojis native to each platform instead of Twemoji images.
In addition to standard emojis, custom Twitter emojis (otherwise known as Hashflags) are enabled for some events and promotions, which are not part of the Unicode Standard.
Twemoji images are part of the twemoji open source emoji project.