The Samsung Galaxy S6 was a critical hit for the South Korean brand, but dropped one of the big things that fans loved: the microSD slot.

Its return on the Galaxy S7 has been lauded as a boost for the new phone, but why did it disappear in the first place when so many other brands, like LG, Sony and HTC, managed to keep it as a key part of their flagship phones?

"At the time we launched the S6, we upgraded all the performance within the device. We upgraded to UFS 2.0, we upgraded to DDR4 RAM… we believed that having a memory card slot would slow down the performance of the device," said Kyle Brown, head of technology, content and launch management at Samsung.

"Thankfully on the S7 we've managed to get the best of both worlds."

About face

The brand launched the S6 with multiple options of internal storage capacity, but that forced the price of the phone up dramatically if you fancied the 128GB Galaxy S6, with many commenters claiming that Samsung was just trying to ape Apple in the way it sold phones.

However, Brown said that it was merely a performance decision, although he didn't comment on why other brands were able to make the technology work, stating that Samsung 'weighed up the pros and cons' of what to include in the device and wanted to make sure design, along with performance, was brought to the fore.

"A lot of people were very disappointed we didn't have a [memory card] slot in the S6, and [its return] has been one of the most positive reactions to the S7. We're really proud of what managed to achieve, adding a microSD slot and water resistive IP68 rating. It's a really massive achievement for engineers."

The idea of the foldable phone is nothing new – but there have been questions over how we could actually use it day to day.

However, Kaz Tajima, senior vice president of creative design and product planning for Sony, told techradar that 'offloading' some of the tasks we have to tap our handsets for multiple times a day to other devices could bring about new form factors in smartphones:

"The smartphone design is getting more mature. The next step with innovation will be coming from the user interface," he said.

"With the current smartphone form factor, every use case is defined by the graphical user interface on a touch display, so we have to have a rectangular form factor, and a certain size of display.

"But the natural user interface, which could be voice command, gesture or eye [tracking], is the next level of innovation. Then we can change the form factor of our smartphone.

"Also another approach is offloading a task to the other device, such as an ear, eye or projector…then smartphones will have a specific use case, so that they may be able to have different size of display, or a foldable display."

Flexible friends

This isn't the first time we've heard about a possible bendy phone though. The technology is being developed by companies such as LG and Samsung, but beyond the slightly flexible G Flex 2, we're not seeing much progress towards new rollable or bendable form factors – so what's holding things up?

"Within a couple of years, as this gesture voice interaction is getting more natural, that will give more freedom to offload tasks to other device, such as [the Xperia Ear]," says Tajima "Then the smartphone doesn't need to cover every kind of task, so that we can change the direction [of design]."

However Tajima warned that just because the opportunity was there, it doesn't mean we'll definitely see flexible phones appearing as extra sensors are littered around our body:

"[Flexible phones] COULD happen, but it will take time, as it's not only the display; the display and battery are the two major [elements] in this form factor… those two should evolve at the same time."

The good news? It looks like they already are, with UK-based firm FlexEnable showing off a fully rollable display at MWC this year, complete with possible touch layers and transistors – so if smart eye, ear and wrist wear become part of our daily lives, it looks like we've got a ready-made solution for a new form of smartphone.

Riding the London Underground every day to and from work can get expensive so MasterCard is offering you three free journeys over the next few weeks, but only if you use Apple Pay.

All you need to do is register your MasterCard with an Apple Pay device and travel on the TFL network between 4:30AM and 01:00 AM on February 29, March 7 and March 14.

You can also travel on any London transport, apart from the Thames Clipper River Bus.

Freebie journeys

To use Apple Pay you will need an iPhone 6, iPhone 6 Plus, iPhone 6S, iPhone 6S Plus or an Apple Watch.

MasterCard has offered free tube journeys before in a similar scheme. The company is fully embracing mobile payments and is using free journeys as a way to open up the technology and show how easy it is to use Apple Pay.

• Everything we know about Apple Pay in the UK