Apple will update its smartphone and tablet lines later this year, not only with the likely introductions of the iPhone 6S and iPad Air 3, but with iOS 9, a new software update set to transform existing iDevices.

Introducing a number of new features, functions and services, the software patch will offer a variety of enhancements, from an improved Siri experience, to battery life benefits and revamped multitasking options. Set to be rolled out in a matter of months, iOS 9 will revitalise iPhone and iPad ownership for millions of users. Here's what you need to know.

What's new in iOS 9?

Unlike in recent years, the iOS 9 update is more about adding new features than a new look and feel. The Apple Watch maker has claimed the update will "elevate the foundations of the platform", addressing everything from search and maps to in-car options and Android migration.

Many of the new iOS 9 features are about bringing the platform into closer competition with Google and its Android OS. This is no more true than with Apple's reworked search offering. Populating your screen with contacts, apps, news feeds and nearby services, Apple wants to give you instant access to the most relevant data possible.

Taking things to the next level, it doesn't want you having to search for information at all where possible. A smarter caller ID system will do all of the leg work for you, looking through your emails in a bid to pair unattached numbers to a name you might recognise. This is just the tip of the iOS 9-themed offering, however.

Notes

Ignored by some, loved by many, Apple's Notes app is set for a sizeable refresh, becoming more relevant and useful to your daily life.

Gaining access from whatever app you're in, Notes will be about far more than a simple location to jot down your latest musings, with checklists, category headings and image, map and URL support all being added. With iCloud backing also joining the mix, the new Notes app will even let you use your finger to create handwritten reminders and image annotations – just like a real notebook.

Maps

Once the laughing stock of Apple's app line-up, Apple Maps has moved on from warped roads, lost locations and bendy buildings. Now a legit challenger to Google's market-leading free service, it's gaining transit directions in iOS 9.

Throwing public transport into the mix alongside walking and driving-based navigation, nearby points of interest, including landmarks, restaurants and cafes will now also be highlighted.

News

One of the biggest new additions to Apple's next software refresh is the introduction of an all new News platform. The company's latest can't-delete app is an imitation of sorts of Flipboard or HTC's Sense skin on Android. News will collate all of the articles you might be interested in, presenting them in one stylish, easy to access location.

With thousands of leading news creators on board for launch, Apple will package the written word alongside all manner of high-production image and video content.

The more you read, the more personalised the service will become, learning your interests and better attuning the promoted content collection to you.

Wallet

Replacing Passbook, Wallet will be the new one-stop app for all things payment-based. Apple Pay – the company's contactless mobile payment service due to launch in the UK later this month – will be managed through the new Wallet platform, gaining new features courtesy of the latest iOS push.

Joining your banking information in your digital wallet, store cards and reward cards are also being cloned, living in your handset for more convenient shopping.

iPad-exclusive iOS 9 features

Introducing something that users of Apple's slates have been requesting for years, iOS 9 will finally bring split-screen multitasking to the market-leading tablet line.

Echoing a number of Android slates, the single-screen, multi-programme options will see users able to have a second app share the screen space equally with another, or display as a small sidebar. The result – more natural, intuitive cross-app collaborations and a smoother, quicker working experience.

What's more, FaceTime will no longer be an all or nothing affair, with the video calling service able to run as a picture-in-picture option while performing other tasks – such as checking your calendar while on a work call, or searching for gig tickets while chatting with your beau.

Siri graduates in iOS 9

Forget 0 ÷ 0-themed backchat, Siri is about to become less gobby and more helpful. iOS 9 will see the voice-activated personal assistant become 40% faster and far more accurate in its feedback. In true Her fashion, it will soon understand context too, allowing for a more conversational tone - creepy.

Siri's updates aren't just about polishing the service, though. In a slightly sinister Google Now fashion, the digital PA will soon be able to pre-empt your likely requests, surfacing information it thinks will be useful before you've even asked the questions.

It does this by monitoring your daily activities, picking up on your regular habits – say, playing music when you get home – and learning when to second-guess your next move and cut out the middle man.

Gaining the ability to search your image library for people and places, in iOS 9 Siri will also gain the skills required to automatically add events to your calendar based on details received in email. She's getting smarter…

iOS 9 will make your devices more secure

If, like many, you use the same four-digit code to unlock your iPhone as you do to get money from a cashpoint, things are about to change. Doing away with four-figure codes in favour of a new six-digit method, Apple is switching the number of possible passcodes from 10,000 to a cool million.

This isn't the only way the Cupertino-based company is keeping your data secure, either. Having pledged not to share your personal information, even between internal Apple services, the company is also adding dual-factor authentication for those with multiple Apple products.

iOS 9 will boost your battery life

Draining batteries are the bane of any smartphone owner. Apple is looking to address this with iOS 9, introducing some clever software tweaks which will better manage your handset's staying power, all without you noticing the difference.

Instead of simply throttling the device in order to conserve power, iOS 9 will use your iPhone and iPad's ambient light and proximity sensors to work out when the device is face down, preventing the screen from turning on, even when you receive notifications.

This is just one of a number of battery usage trimmings which will add up to around an hour's additional use on a single charge, a figure not to be sniffed at.

What is iOS 9's release date - and is there a beta?

Keeping with tradition – and its annual launch cycles – Apple first debuted iOS 9 during its annual developers' conference back in June, confirming the software would be rolled out to consumers this 'fall'. Although an exact release date has yet to be announced, it is expected that the patch will launch in mid-September, in the days leading up to the company's next smartphone introduction.

Can't wait till the autumn? Well Apple has decided to be kind and give you an early play. An iOS 9 public beta will be held months ahead of launch for those too impatient to wait. With iPhone and iPad owners able to register their interest now, the public beta programme will officially kick off on an as yet undetermined date later this month.

This is the first time Apple has offered a public beta on its iOS software having previously limited avid fans to Mac OS X previews.

Is my device iOS 9 compatible?

Unlike when new Android updates drop, Apple is pretty hot in ensuring most existing smartphone and tablet owners are offered the patch on day one. iOS 9 is no exception, heading to all versions of the iPhone and iPad launched in the past couple of years.

On the phone front, everything from the iPhone 4S onwards – yes, that includes your recently purchased iPhone 6, don't worry – will be offered iOS 9 in some capacity, while all but the original iPad will make the move on the tablet side.

Still clinging on to an iPod touch? Sadly, only the fifth-gen offering will be making the move to the new OS.

The iOS 9 diet

Last year, iOS 8 saw Apple's annual software update cause millions of users to struggle for storage space. Lining up at 4.58GB in size, the hefty patch forced many to delete apps, photos and files in order to free up the necessary space.

For 2015 the new iOS update has been trimmed and toned down, requiring just 1.3GB of available space. Hopefully this should do away with storage concerns for most.