CUPERTINO — Apple has unveiled the first foldable iPhone in the company's history, introducing a radical redesign of its most important product less than two weeks into John Ternus's tenure as chief executive.

The new device, called the iPhone Duo, folds open like a book to reveal a 7.6 inch display, giving users a screen closer to a small tablet while retaining the ability to fold into a pocket sized smartphone.

Apple announced the device on Wednesday during its annual September product event, marking its entry into a foldable smartphone market where Samsung, Huawei and other manufacturers have competed for years.

The iPhone Duo will start at $1,999 in the United States and £1,999 in the United Kingdom, making it one of Apple's most expensive iPhones.

Preorders will begin on October 16 before the device becomes available in more than 70 countries and regions on October 23.

For Apple, however, the significance of the Duo extends beyond its price.

The launch represents one of the biggest changes to the physical design of the iPhone since Steve Jobs introduced the original device in 2007 and comes at the beginning of a new leadership era following Tim Cook's departure as chief executive.

An iPhone that opens into a tablet sized screen

The Duo has two displays.

When closed, users interact with a 5.4 inch outer Super Retina XDR display. Opening the device reveals a 7.6 inch inner Super Retina XDR screen designed for video, gaming, reading and running multiple applications simultaneously.

Apple says the inner screen is 50 percent larger than the display on the iPhone 18 Pro Max.

The company has also redesigned iOS 27 for the foldable format.

Users can open two applications side by side using Split View, save pairs of applications they frequently use together and move between the outer and inner displays as the device is folded and unfolded.

Apple says applications including Netflix, Zoom and Slack are already being adapted to take advantage of the larger display.

The company has attempted to minimise one of the most noticeable characteristics of existing foldable phones, the crease that can appear where the display bends.

The Duo uses a nano textured inner display and a precision hinge designed to keep the screen flat when fully opened.

The body is made from grade 5 titanium and will initially be offered in star white and night sky.

Later this year, the Duo will also support Apple Pencil.

Ternus takes centre stage

The launch is particularly significant for John Ternus, who recently succeeded Tim Cook as Apple's chief executive after spending years overseeing the company's hardware engineering operations.

Ternus played a major role in Apple's hardware development before taking the top job, making the company's first foldable iPhone an important early test of his leadership.

“iPhone Duo is the most transformational change to iPhone since the original,” Ternus said.

Apple is betting that its late arrival in the foldable market will allow it to address some of the problems that have limited wider adoption of the technology.

Samsung began selling foldable smartphones in 2019, while Huawei and other manufacturers have developed their own competing devices.

Foldables nevertheless remain a relatively small part of the global smartphone market.

Apple's enormous installed customer base and the continued importance of the iPhone to its business mean its entry could significantly increase consumer awareness of the category.

New hardware inside the Duo

The iPhone Duo is powered by Apple's new A20 Pro processor and uses a dual battery architecture alongside a redesigned thermal management system.

It also includes Apple's C2 cellular modem and N1 wireless networking chip, supporting WiFi 7, Bluetooth 6 and Thread.

Photography remains a major part of the device.

Apple has equipped the Duo with a 48 megapixel Fusion Main camera and 48 megapixel Fusion Ultra Wide camera.

The folding design allows users to take photographs using the higher quality rear cameras while viewing themselves on the outer display.

Another feature allows people being photographed to see a live preview of the image from the opposite side of the phone.

Apple has also placed a FaceTime camera beneath the inner display to keep the larger screen uninterrupted when the camera is not being used.

Storage options range from 256GB to 2TB.

Apple pushes deeper into AI

The hardware launch comes alongside Apple's broader attempt to strengthen its position in artificial intelligence.

The company is expanding Apple Intelligence and introducing Siri AI, a substantially redesigned version of its voice assistant.

The new system is designed to use information stored on a person's device, including messages and other personal context, to answer questions and carry out tasks.

Apple is placing privacy at the centre of its AI strategy.

Many AI operations will run directly on the device rather than sending personal information to external servers.

When more computing power is required, Apple says its Private Cloud Compute infrastructure will process requests while protecting user data.

Siri AI is scheduled to begin rolling out in beta with iOS 27 on September 14 for supported devices in English, with additional languages expected later.

The combination of foldable hardware and artificial intelligence gives Ternus an opportunity to demonstrate that Apple can still create major changes to the iPhone while responding to growing competition in AI.

Apple enters a market Samsung helped create

Apple's arrival also creates a new competitive battle with Samsung.

Samsung has spent years developing its Galaxy Z Fold devices and responded quickly to Apple's announcement by highlighting its experience in foldable smartphones.

Apple's entry is nevertheless expected to expand the overall market rather than simply redistribute existing foldable customers.

The company has historically entered some product categories later than competitors before attempting to make them more mainstream.

Whether the Duo can achieve that with foldable smartphones will depend partly on whether consumers believe the larger display and new capabilities justify its premium price.

At $1,999 before higher storage configurations and accessories, the Duo sits well above conventional flagship smartphones.

That makes it a test not only of Apple's engineering but also of how much customers are willing to spend for a substantially different iPhone experience.

A new chapter for Apple's most important product

The stakes are significant because the iPhone remains at the heart of Apple's business and accounts for more than half of the company's annual sales.

Nearly two decades after the first model transformed the smartphone industry, Apple is attempting to change the familiar shape of the device without abandoning the experience that made it successful.

The Duo will provide the first indication of whether consumers are ready for that change.

Preorders begin October 16, with sales starting October 23 in the United States, United Kingdom, Canada, China, India, Japan, South Korea, the United Arab Emirates and dozens of other markets.

For Ternus, the launch also provides an unusually high profile beginning to his tenure.

His predecessor, Tim Cook, inherited a company whose defining product had already been established.

Ternus begins his tenure with the task of convincing customers that, almost 20 years after the original iPhone, Apple can reinvent its most important product again.