Virtual reality was a key theme in the demos and debates at this year's Mobile World Congress. The Barcelona trade show even saw the Facebook CEO, Mark Zuckerberg, make a surprise appearance at Samsung's press conference to extol the technology's virtues. MWC saw new VR devices on show and brought industry insight into the future of the tech market's hottest new trend.

There were all manner of virtual reality headsets at this year's MWC, with advanced models alongside basic VR viewers. The headline-grabbing Samsung Gear VR, on sale since the end of 2014, for example, is now being bundled as a freebie with preorders of the Galaxy S7 and Galaxy S7 Edge smartphones placed before March 10, 2016. The South Korean manufacturer is clearly keen to get VR out into the mainstream.

Rival South Korean firm LG presented a pair of virtual reality goggles that hook up to its new G5 flagship smartphone. This has two built-in screens that simulate the image of a 130-inch TV from two meters away. As yet, there's no word on its price or release date.

Alcatel, on the other hand, had the original idea of turning the packaging of its Idol 4 Plus and Idol 4S phones -- presented in the Spanish capital -- into a VR viewer. In theory, this looks closer to Google's Cardboard VR viewer than an advanced headset.

Finally, HTC has announced the price and release date for its Vive VR headset. Developed in partnership with video games studio Valve, it'll be up for preorder on February 29, 2016, priced $799, with shipping expected to start in April.

Mark Zuckerberg sees the future in VR

The Facebook CEO believes that VR will be about more than just gaming and entertainment. In fact, it could be set to change the face of social networks very soon.

Preparations are already underway to optimize Facebook as a platform for the millions of 360-degree videos that users will want to upload to share immersive experiences with friends and family across the globe. Facebook's servers are being brought up to speed to broadcast live, high-quality 360-degree image streams while using the least bandwidth possible.

Other major tech firms are branching out into the VR too, such as Microsoft with its ambitious Hololens project. Apple is also rumored to be working on its own virtual reality system.