Enlarge Image Juan Garzon/CNET

Samsung last Wednesday offered the first glimpse of its upcoming foldable phone, saying it'll be mass produced "in the coming months."

Justin Denison, Samsung senior vice president of mobile marketing, showed off the phone, which is a tablet when it's fully opened and then a phone when it's closed. It uses a new display technology called Infinity Flex Display that lets you open and close the device over and over without any degradation.

"The Infinity Flex Display represents an entirely new mobile platform," Denison said. "We've been living in a world where the size of your screen can only be as large as the device itself. We've added a new dimension to help you browse, watch and multitask like never before."

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The device he showed isn't the final product. It's likely the phone Samsung releases will be sleeker and have smaller bezels than the device Denison demonstrated.

"The success or failure of Samsung's first folding phone will depend on how well Samsung has been able to button up the device." CCS Insights analyst Ben Wood said. "If it's a slick, attractively designed device it will be a magnet for gadget lovers. If it is bulky and hard to use it will be a tougher sell."

The foldable phone can run up to three apps at the same time, something Samsung calls Multi Active Window. Google's Glen Murphy, head of Android UX, took the stage after Denison and said Android will support the new foldable display technology.

Denison added that Samsung's also working on technology for rollable and stretchable displays.

Samsung made the announcements at its fifth annual developers conference, taking place Wednesday and Thursday in San Francisco. The event, which started off small at a San Francisco hotel, in 2016 expanded to Moscone Center West, where Apple previously held its developer conference. Last year, 5,000 people attended SDC.

Juan Garzon/CNET

SDC reflects Samsung's big push to get developers to make software specifically for its devices. In the past, that's meant making apps that work on the edge of Samsung's curved smartphone displays or take advantage of its S Pen stylus. This year, that focus has turned to Bixby and artificial intelligence.

Samsung has been chasing the holy grail of a foldable phone since it teased one at CES 2013 by showing off a flexible OLED display. The device comes at a tough time for the mobile market. Apple and Samsung handset sales are slowing, and the global smartphone market is said to be in recession. Foldable phones could mark the next big innovation in mobile devices -- as long as they're not too gimmicky.

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D.J. Koh, CEO of Samsung's mobile business, told CNET in an October interview that you'll be able to use the device as a tablet with multitasking capability before being able to fold it up into a more portable phone. He once again stressed that the foldable phone wouldn't be a "gimmick product" that would "disappear after six to nine months after it's delivered."

"When we deliver a foldable phone, it has to be really meaningful to our customers," Koh said last month.

Now playing: Watch this: Samsung's foldable phone will use One UI

Foldable phone specs

During a Wednesday afternoon panel with developers, Samsung gave more details about the hardware coming to its upcoming foldable device. The company aims to have battery life that lasts as long as current Galaxy smartphones, said Jisun Park, engineering director and head of the system software group for Samsung's mobile business. That's despite the fact there's more screen to drain the battery.

Enlarge Image Shara Tibken/CNET

The Cover Display, what you'll see when the device is closed and looks more like a regular phone, is 4.58 inches and has a 21:9 aspect ratio. Samsung says it has a resolution of 840x1960, with a screen density of 420 dpi.

"Compared to the Main Display, the experience is more ... optimized for focused and handy and quick access and interaction, to leverage the small screen," Park said. When the device is unfolded, the Cover Display will turn off and go black, he added.

The Main Display, the bigger screen you see when unfolding the phone, is 7.3 inches and has a 4.2:3 aspect ratio. Samsung says the resolution is 1536x2152, with a screen density of 420 dpi.

.@Flipboard is working on an app for @Samsung’s new foldable phone. When closed, you’d see a single pane of info. When you unfold the phone, you get a bigger panel (right where you left off on the closed display) and multiwindows #SDC18 pic.twitter.com/08PiAUvY3I — Shara Tibken (@sharatibken) November 7, 2018

"Unfolding the phone provides more information with visual cues," Park said. He noted that it's key for Samsung to get developers on board to build its ecosystem to take advantage of the multiple screens.

Claus Enevoldsen, a marketing executive from Flipboard, showed off an app his company has been working on for Samsung's foldable phone. Samsung and Flipboard have worked together for years, with the news app given prominent positioning on Galaxy phones.

When closed, you'd see a single pane of information in the Flipboard app, much like what you normally see on the smartphone version. When you unfold the phone, you get a bigger panel -- that's displayed to the same point where you left off on the Cover Display -- and multi-window support.

"We want to lean in and take advantage of everything possible with this form factor," Enevoldsen said.

First published at 11:30 a.m. PT

Update at 4:25 p.m. PT: Adds spec details from a panel.

Update at 5:35 p.m. PT: Adds analyst comment.

Update Nov. 13 at 10:24am PT: Adds more video

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