Samsung has provided the public a first look at its new foldable smartphone.

The device was shown for the first time Wednesday during a Samsung developer's conference in San Francisco, California.

The South Korea-based technology company first announced plans to build a fully foldable phone five years ago.

The phone is designed to fold open to make the device the size of a small tablet. It can also perform some operations of a tablet. When folded closed, the device looks and works like a normal smartphone.

Justin Denison is Samsung's senior vice president of mobile product marketing. He introduced the device to people at the conference.

"Ladies and gentlemen, I give you the future of mobile display technology – the Infinity Flex Display."

Denison demonstrated the device, which he said marked a major breakthrough in future smartphone technology.

"It's finally here. When it's open, it's a tablet, offering a big screen experience. When closed, it's a phone that fits neatly inside your pocket."

Denison said the design and development of the foldable device was very complex. He said Samsung had to invent new manufacturing materials and methods and "re-imagine the display from the ground up."

He said one of the biggest difficulties was finding a material that was flexible, but also strong enough to support repeated folding and unfolding of the device.

He said the Infinity Flex Display was designed to smoothly operate continuously when opened and closed. Denison said the device will permit users to keep up to three apps open at one time. With normal size smartphones, users have to keep changing between apps.

"We have been living in a world where the size of a screen could only be as large as the device itself," Denison said. "We have just entered a new dimension."

He said Samsung will "be ready to start mass production in the coming months." No launch date has been announced. A message at the end of Denison's presentation said only that the devices would be "arriving soon."

Reuters reports that a top Google engineer spoke about a new Samsung device at a Google conference in California. The engineer said Samsung planned to introduce a new device with an Android operating system early next year. The engineer also said several other Android manufacturers were also working on foldable products.

Technology experts see the new foldable design as a way to get users to buy a new device seen as revolutionary. More people are deciding to hold onto smartphones longer because newly launched models do not offer major improvements and can be very costly.

This behavior is one reason for a steady decrease in worldwide smartphone sales over the past year. Research company IDC reported smartphone sales fell by 4 percent during the 12-month period ending in September 2018.

Samsung, the world's leading seller of smartphones, suffered a 7 percent drop during the period, IDC said.

It remains to be seen whether foldable phones will become popular quickly. The devices are expected to cost more than $1,000.

Royole is a small California company hoping to sell early versions of a foldable-screen phone in the U.S. for $1,300 to $1,500. The company has not yet announced when its FlexPai device will be available in America. But it is planning to launch the product in China starting next month, at a price of about $1,300.

I'm Bryan Lynn.

Bryan Lynn wrote this story for VOA Learning English, based on reports from the Associated Press, Reuters and the Samsung Developer Conference. Mario Ritter was the editor.