Apple's iOS 9 launched today and is now trickling out to your iPhone and iPad, and the big update brings a smarter Siri, public transit directions to Maps, true tablet multitasking and new built-in apps.

iOS 9 became available to download today at 10:00am PDT, 1:00pm EDT, 18:00 BST, so check the software update menu within settings for that all-important over-the-air updated at that time.

It's the company's latest software, available to just ahead of the release dates for iPhone 6S, iPhone 6S Plus, iPad Pro and new Apple TV, all revealed during September 9's keynote.

iOS 9, and iOS 9.1 beta for testers, has improved stability, a smaller download size and legacy phone and tablet compatibility. That older iPhone and iPad you have works with this update if it runs iOS 8.

New iOS 9 features consist of redesigned built-in apps and a few new ones. There's more multitasking functionality than ever for iPads, while 3D Touch and motion wallpaper are coming for new iPhones. That will make new rose gold iPhone 6S color really pop.

iOS 9 compatibility

iOS 9 is proving to be more inclusive than previous iOS versions. Apple is choosing to make this update compatible with older iPhone, iPad and even iPod touch devices, too. Okay, it's not technically more inclusive beyond the immediately launched iPad mini 4. The iPhone 6S and iPhone 6S Plus still have to launch next Friday, September 25, and the iPad Pro lands sometime in November. Then the list will grow by three. It'll become a total of six when the iPad Air 3 and iPhone 6C eventually release.

Basically, right now, if your dated hardware runs iOS 8, it can run iOS 9, and that's good news, as older phones and tablets aren't getting muscled out. The iPhone 4S and iPad 2 are safe, for now, and a few 30-pin dock devices live on for another year.

iOS 9.1 update

Before we dive into new iOS 9 features, we can already explore what's even newer in iOS 9.1, which is now available to beta software testers using a compatible iPhone, iPad and iPod touch.

As you can see from the screenshot above, it include new emojis, including a taco, burrito, unicorn face, hot dog, popcorn, turkey and cheese wedge, and yes, even a silly middle finger.

This over-the-air update may also bring new compatibility to the iPad Pro, with its high resolution screen and Apple Pencil stylus, but so far there are new detailed release dates.

iOS 9.1 can be downloaded through the Apple Beta Software program (instructions above), and should be available to everyone else soon. iOS 8.1, for example came out in October

Smarter Siri

Siri in iOS 9 gets the much-needed smarts to rival Google Now. Apple's personal assistant understands the word "it" within context and brings proactivity to the operating system.

For example, if you're talking about a topic with someone in iMessages and ask Siri to "Remind me about 'this' later today," it'll scan the open app and try to understand what "this" means.

iOS 9 proactivity puts even more at your fingertips through Siri. It suggests appointments to add to Calendar, and pulls up photos based on location and time with the sound of your voice.

Siri's location-based knowledge appears to be most promising when you're out and about. Plugging in headphones at the gym? It offers the Now Playing interface right on the lockscreen.

Plugging it into your car? It brings up that audiobook you were listening to before. It even tells you when to leave for an appointment across town, a feature that has made Google's app for iOS a must-have.

Saying "Hey Siri" to issue commands while untethered from the usually-required light cable is going to be possible, too. However, this iOS 9 feature has only been announced for the new iPhone 6S and iPhone 6S Plus.

One of the most convenient new iOS 9 features is giving context to random numbers that call you, diving into your email to see if it can match the digits. Goodbye, telemarketers – we hope.

Siri already takes over one billion requests a week, according to Apple. That should only increase now that iOS 9 promises to make Siri 40% faster and 40% more accurate.