Flip phones ruled the mobile world until smartphones took over with their touchscreen slabs. However, we might soon be folding our phones in half again – if Samsung has its way.

Foldable smartphones are coming, and as with curved screens - from the Galaxy Note Edge up to the Galaxy S8 and beyond - Samsung appears to be leading the charge. For a few years now, the company has been sharing concepts of foldable and rollable smartphones, and a flurry of patent applications and rumours suggest the first models are coming very soon.

Samsung intends to make fully functional smartphones with flexible displays that allow you to fold the phone shut and tuck it in your pocket – and maybe even phones that open up to reveal a full-sized tablet screen within, or touchscreen devices that roll out of a tube.

Sound crazy? Maybe. Seem expensive? Undoubtedly. Is it exciting? Absolutely. Here's everything we know about the so-called Galaxy X phones so far.

Setting the table

What you might not realise is that Samsung has been quietly preparing us for this future for the past several years. Back in 2011, Samsung released a concept video that showed a flexible AMOLED phone that's little more than a technological piece of translucent paper: much more advanced than what's actually coming anytime soon, but a truly inspired creative spark all the same.

Much more realistic is the above video that shows a smartphone that opens up to become a tablet – or rather, a tablet that folds in half to reveal a smartphone on the outside. However you choose to frame it, we've heard that idea come up again in a recent report, so it might be pretty close to the real thing.

We suspect that Samsung has been waiting for the tech to match its ambitions, but that timetable keeps shifting. In early 2015, a Samsung Display representative said that "the commercialisation of foldable smartphones will be possible in 2016."

Indeed, Samsung was apparently so far advanced with its plans that it was reportedly showing off the new phone behind closed doors at this year's Mobile World Congress. It was a prototype, admittedly, but the investors and mobile operators that saw it were reportedly "very impressed" with the concept.

The wallet phone

From the outside, in its fully open and extended state, the Galaxy X phone could look pretty similar to a typical Samsung flagship phone: it has one large touchscreen on the front, cameras on both sides, and perhaps a home button below the display. It's a smartphone.

Only this smartphone does something quite surprising: as this patent application illustration shows (via Patently Mobile), the phone can fold right in half, fully covering the screen and making the phone about half its normal size. That makes it more pocket-friendly, plus it keeps the display nicely ensconced within the shell.

On the outer edge of the hinge is a charging contact, not unlike those seen on smartwatches, and you can pop the Galaxy X phone into a charging cradle to juice it up. Unfortunately, that suggests that the phone cannot be used while charging, much like wearable devices, since the contact is hidden while the phone is fully open. Guess that's the price of advancement, huh?

How does it work?

That's the most realistic Samsung illustration we've seen to date of the foldable design, but there have been other sketches and concepts seen over the last couple of years. One constant has remained true between them: that amazing new hinge system.

Samsung reportedly calls this initiative "Project Valley" because of that hinge: essentially, it creates a little pocket for the touch display to fold up without ever creasing. That small valley allows the phone to fold flat while allowing enough space for the screen have a slightly curve, preventing unsightly seams from appearing.

And then when you unfold the phone, the screen becomes fully taut, making it a properly useable smartphone. We're curious how different the screen will feel given the lack of outer glass, but we have to assume Samsung has found a way to make it work.