Hello, Proactive. iOS 9 arrived today!

iOS 9 is arriving today. But what we saw on stage at Apple's World Wide Developer Conference this spring was more than just a yearly update to Apple's mobile OS. It's a glimpse at how Apple's operating systems are being unified as it builds out new devices and platforms. iOS has never mattered more.

Hello, Proactive

The headline feature in iOS 9 is intelligence. Not only is Siri smarter and more aware—she can set up reminders, for example—but Apple has created an entirely new feature called Proactive. It's a new assistant that will learn your behaviors and predict what you're interested in doing with your phone.

Craig Federighi explained how Proactive works across many different apps and use cases as he took us on a tour of his day-in-the-life with iOS 9:

For example, say you usually plug in your headphones at a certain time of day and listen to a specific kind of music at the gym. Proactive will “learn” that behavior over time and start to suggest it, as Federighi demonstrated.

Proactive can also do things like suggest who unknown callers might be when a number pops up on your screen. It might suggest apps that you tend to use during certain times of day—or even suggest locations nearby. There's also an API for search, an update that was met with wild applause from the crowd. This kind of functionality will feel familiar to Google Now users, but for iOS fans, it's a major update.

Transit, Notes, and News

iOS 9 introduces one entirely new app, in addition to big improvements to Maps and Notes.

First up, we saw a long-awaited and desperately-needed addition to Mapsthat includes public transportation routes and other contextual tweaks. It remains to be seen if it will work as well as Apple says it will, but it sure seems more useful, with routing for subways, buses, and other forms of public transit. It will also tell you details like where to enter the subway for the fastest access to the correct train. There's better search functionality, too, as well as a predictable Apple Pay tie-in. Apple wants you to know that Shake Shack takes Apple Pay before you trek up there!

Then there was News, a brand-new free app that will replace Newstand (RIP) and look a bit like Flipboard, (as Re/code first reported this morning). News looks like a simple, clean way to read on your iPhone that pulls content from The New York Times, the Atlantic, Bon Appetit, and many more. Here's the demo from today's keynote:

Goodbye, Newstand. We hardly knew ye.

Security & Privacy

Security was another major talking point today—finally, Apple is enabling two-factor authentication for your ID.

After all, now that this more intelligent and observant iOS will have more information about how, when, and where you use your phone, privacy will become a bigger issue. While Federighi didn't spend a ton of time on iOS, he did spent a large percentage of the presentation promising that Apple won't be collecting that data on your usage—saying it will be anonymous, and based on a randomized identifying number.

Multi-tasking For iPad

The inability to work in two apps at once has long plagued iPad users who want to do anything beyond reading or internet scrolling. Today, Apple introduced three new features for multi-tasking on its tablets.

Let's start with the things you'll be able to do on the most models. First, there's Slide Over, which lets you swipe a secondary app over onto your screen from the right side to interact with it while you keep a primary app open. Then there's Picture-In-Picture, which will let you keep a video playing in the corner of your screen while you work in a different app—as Federighi showed us by keeping an ESPN video playing while he worked.

Finally, a feature called SplitView actually lets you divide your screen real estate between two apps and still scroll and work in both of them. This is the multi-tasking functionality many users have been waiting for, with one major caveat: It will only work for the iPad Air 2. This seems to suggest that SplitView is really meant for the workplace-focused iPad Pro we've heard rumors about for so long.

The Size

It's been a year since the 4.6 gigabyte debacle of iOS 8. And it seems that Apple took note of the outrage and exasperation users felt while trying to update their devices. The size of iOS 9? A mere 1.3 gigs.

How Can You Get It?

iOS 9 will be available as a free upgrade on September 16, and it will come as good news to older iPhone users that no devices will be dropped from this release.