SwiftKey (in beta) and Google Keyboard both support emoji on Google Android today. Apple iOS has supported it for a long time now. This means that you are likely to be seeing emoji on social platforms and instant messengers for a while now.
Google Chrome does not support emoji by default (on Windows at least). There are a couple of extensions available which adds support for it.
Emojify is one of the popular ones that uses the Google’s version of emoji from Hangouts. The app also lets you add emoji through a custom on-screen keyboard as well.