There are more ways to communicate online than ever before. Yet millions of people still use email to interact with one another.

You may use Slack to talk with work colleagues and Facebook Messenger to chat with friends, but chances are you still go — often begrudgingly — back to your email inbox throughout the day.

There is no shortage of email apps to choose from, and many of them, like the recently shuttered Mailbox, have made it significantly easier to manage our hectic inboxes.

But none are quite like Inbox by Gmail. Yes, that Gmail — the email service from Google.

On the surface, Inbox may look like just another cool email app that happens to come from a giant tech company. But don't be fooled — Inbox is actually an ambitious effort to rethink how email will work a decade from now.

Writing your emails for you

Inbox has all of the basics you would expect from Gmail, like the ability to bookmark (or pin) emails, move them to folders, and batch delete. It also has power user features you may know from other email apps, like the ability to snooze emails for later.

But Inbox primarily serves as a playground for the Gmail team to experiment with artificial intelligence, or as Google calls it internally, machine learning.

Google uses machine learning to power everything from how it sorts search results to how it filters the barrage of spam that tries to get your attention.

But when it comes to Inbox, the most complex example of machine learning is a feature Google announced in November 2015 called Smart Reply. By analyzing the contents of an email, Smart Reply gives you three quick responses it thinks you might want to choose from.

And it's the kind of thing that feels like magic when it works.

"I wasn't sure if it was even possible," Greg Corrado, a senior research scientist at Google who worked on Smart Reply, told Tech Insider. "But it was such an exciting opportunity that we couldn't help but try."

Corrado, who belongs to the elite group of researchers who make up the Google Brain team, had already worked on machine learning used in spam classification and Gmail's Priority Inbox, a feature that sorts important messages from less important ones. He said that Smart Reply was born out of the team wanting to know if machine learning could be used to respond automatically to emails in a human-sounding way. The feature ended up taking a year to be built.

When you open a new email in Inbox, Google's computers summarize its text into a machine readable format called a "thought vector," he explained. Each vector is informed by a field of scientific research called sentiment analysis, or the idea that a computer can understand the general tone and intention of a piece of text.

The end result is an email from a colleague about vacation times creating a thought vector with three possible responses that are suggested in the app.

Google could have produced anywhere from one to 500 possible responses per email, but the team designed the feature to be as simple and helpful as possible. "We really wanted something that wouldn't try to say the same thing in three different ways," Corrado said.

The natural extension of Smart Reply would, of course, be generating responses longer than one line and then eventually entire conversations. Could Smart Reply one day analyze an entire email thread, learn the context of a conversation, and write paragraph responses for you? Corrado laughed when I posed the question.

"I think that if we could build such a system that would amount to passing the Turing Test," he said, referencing a scientific test developed by Alan Turing in the 1950s that determines whether a computer is capable of communicating like a human being. "We're not anywhere close to that."

So for now, it's baby steps.

The future of email

There is perhaps no person better qualified to talk about the future of email than Alex Gawley, who oversees Google Calendar, Inbox, and the now 12-year-old behemoth that is Gmail.

"The world has changed a lot since 2004," he said, referencing the year that Google introduced Gmail. He pointed out that the most popular web browser at the time was Internet Explorer 6. Firefox had not been released. Smartphones as we know them now were years away.

The idea that became Inbox started being discussed internally at Google a couple of years before it was announced in October 2014. "We felt that there was an opportunity to rethink [email] and think about what might an inbox for the next 10 years look like," Gawley said.

The Gmail team then set out to build a completely new email experience with mobile and machine learning at its core.

"There's this transition from tools to assistants and computers doing a lot of the work for you," he said. "So how can we build an inbox that really did a lot more of the work for you?"

His team observed that Gmail users were spending lots of time manually bundling and moving emails into different folders and assigning different tags. So Inbox automatically groups emails, whether they're newsletters or work updates, into bundles to simplify the management process.

The team also saw that 80% of searches in Gmail were looking for a fact in an email rather than the email itself. So the group designed Inbox's search tool to get you to an important fact or something you want to act on, like the gate number for your flight. "You care that your flight departure was changed, not the email underlying it," Gawley explained.

The same principle is applied to a feature in Inbox called Highlights, which automatically lifts the important information out of an email and displays it above the rest of the message. It's particularly useful for Google Calendar invites because Inbox shows you all of the event info at a glance and lets you accept or deny the invitation without even opening the email.

It's the "inbox that helps you get back to everything" ethos Gawley described that informs how the app integrates with Google Reminders, a smart to-do list. Not only can you add a reminder while looking at an email and flip through them at the top of your inbox, but Reminders will even occasionally suggest a reminder for you based on the contents of an email.

The rise of machine learning

"I would really like you to be doing the work in your inbox that only you can do," Gawley said when asked how email will be used in 10 years. "That means the creative work, the work where you're interacting with someone on a human level. Whereas when I look at the work that most people are doing in their inbox right now, most work is mechanical. Most of it is moving things around between labels or archiving things or deleting things."

Alex Gawley has been a product director at Google for over 7 years and currently oversees Gmail and Google Calendar. Google Google is in a unique position to build something like Inbox. It has extensive expertise in machine learning and a large Rolodex of popular productivity apps. Gawley foresees Inbox being able to hook deeper into existing Google services, like Calendar and Google Drive. Imagine that when you recieve an email asking when you're free for a meeting, Google Calendar suggests when you're available.

Inbox is made by the same team that works on Gmail, and it remains a project "we're really committed to," Gawley said. "It gives us the opportunity to be a little more aggressive and learn where the boundaries are." Launching Inbox as a separate app gave Gawley's team a group of users who are choosing to take part in a new, cutting edge email experience.

The pace at which Inbox innovates and informs how Gmail proper works will depend on how quickly Google's machine learning brain can learn from itself and the behavior of those who use the app. Gawley would rather lean on computers to make Inbox smarter than human engineers. "They can write a lot faster than we can write code."