Snapchat introduced the Stickers feature in May 2016, following the Facebook Messenger. Then it added about 320 stickers to its app at once - and they became immediately available for all those users, who had the latest update installed. This was just the beginning of the stickers craze, as their list has been constantly increasing with the possibility of creating and adding custom stickers.
The original Snapchat stickers are characterized by design, which looks more like hand drawing than digital artwork - the custom ones may look in any way. And as for their essence, they are just what they are in all the other apps - the bright and colorful emoji-like images, not limited to the traditional emoji set, which render exactly what they depict. They may be placed on the snap, including the popular option of putting stickers on the moving things in the video, or in the chat message.
The examples of Snapchat stickers are endless - some of them represent different foods like McDonalds fries, masks like animals' faces, various characters doing something, different accessories and face features to be put on the user's face on the photo or video snap like mustache or crowns, and numerous phrases.Image source: http://mashable.com/2016/05/24/snapchat-stickers/#FwBylxG3ISqK