Apple introduced a foldable iPhone overnight on Wednesday, making the most significant change in 19 years to the company’s most important product.

During a 75-minute recorded presentation at its headquarters in Cupertino, California, Apple unveiled the iPhone Duo, a foldable smartphone with a bendable display that opens and closes like a book. When folded, it will be similar in size to a passport. When it’s open, consumers will be able to use two apps at the same time across a larger display. The phone will start at $US1,999 ($2770) and will be available October 23. However, in Australia the same device’s price starts at $3499 and goes up to $5899.

“Others have created foldables that just feel like two phones awkwardly stuck together,” said John Ternus, Apple’s new CEO. The new Apple phone, he added, “will redesign the experience of using a foldable phone.”

Foldable smartphones have been commercially available since 2018, but the category has not yet made inroads with consumers. Last year, consumer electronics companies shipped nearly 20 million foldable phones — or less than 2 per cent of all smartphone shipments — according to Counterpoint Research, which tracks smartphone markets.

Apple’s product event on Wednesday was Ternus’ first since taking over leadership of the company. He was the company’s head of hardware engineering before succeeding Tim Cook as chief executive last week. In the recorded presentation, Ternus emphasized Apple’s work on artificial intelligence and described iPhones as the ideal device to be a “personal intelligent hub.”

Over the nearly two decades since it debuted in 2007, the iPhone has become Apple’s biggest business, now accounting for half — or more than $US200 billion — of its annual revenue. The business has continued to grow, even as the iPhone has faced criticism for improving only incrementally.

With the iPhone Duo, Apple is establishing a new high end for its lineup of phones and trying to prove that it can still create innovative products.

The iPhone Duo is hitting the market in a difficult environment for consumer electronics. The artificial intelligence boom has created a global shortage in memory chips, making the component more expensive for devices such as phones, computers and video game consoles. In June, Apple increased the prices of Macs and iPads. In July, said it expected to pay even more for memory in the current quarter.

The foldable iPhone is “part of experimentation around how to continue to grow iPhone” as a business, said Gene Munster, a managing partner at Deepwater Asset Management, an investment firm. “They think about this holistically and how they can continue to turn the screws to get you to move higher” in the product lineup, he added.

The iPhone Duo could add significantly to the market for foldable smartphones, but it would remain a slice of the overall market for phones. Next year, Apple is expected to ship more than 12 million foldables — 5 per cent of all iPhone shipments — according to Counterpoint.

On Wednesday, Apple also updated traditional models of the iPhone. The iPhone 18 Pro will have a new chip, the A20 Pro, that allows it to run Apple’s most advanced AI models. Apple extended the phone’s battery life, so it can play videos for 36 hours on the iPhone 18 Pro and for 48 hours on the iPhone 18 Pro Max. The phone also has a new system of cameras, including one that can change how much light it lets in.

Both models will be $US100 more expensive than their predecessors. The iPhone 18 Pro will start at $US1199 (it will retail at $2099 in Australia) and the iPhone 18 Pro Max will start at $US1,299.