Smart Reply is Google's attempt of showing its commitment towards machine learning. So, basically, Smart Reply will offer three suggestions in response to the messages you receive. You can get to choose from one of them or simply ignore all and write your own reply.
It follows the principle - the more you use it, the more it learns your response behaviour and improves with time. So, you'll start getting better suggestions with time. "Smart Reply utilises machine learning to give you better responses the more you use it. So if you're more of a “thanks!” than a “thanks.” person, we'll suggest the response that's, well, more you," Google writes in a blogpost.
"Once you’ve selected one, you can send it immediately or edit your response starting with the Smart Reply text. Either way, you’re saving time," the blogpost reads.
Now, this isn't something new and Inbox by Gmail and Allo already have these features. In fact, Google claims that about 12 percent of replies sent from Inbox for mobile were Smart Replies.
It is rolling out on Android and iOS in English, but Google plans to add more languages soon.