Microsoft reveals Windows 10
Technology giant Microsoft has shown off Windows 10 to the world for the first time, saying: "Today really is a monumental day for Windows," and confirming the software will be available free for those running the current version of Windows.
Microsoft's Terry Myerson said: "Windows 10 will support the the broadest device family ever. Since September we've received a lot of feedback ... feedback is shaping the future of Windows.
"For the first year after Windows 10 is available, we will be making available a free upgrade to Windows 10 for all devices running Windows 8.1. Once a device is upgraded to Windows 10, we'll be keeping it current for the supported lifetime for the device.
"Windows 10 is so much more than the latest version of Windows. Windows 10 changes the rules of the game."
The new software has reintroduced the famous "Start" menu that was removed from Windows 8. It can now be shifted between the traditional smaller and full screen view.
Microsoft's Joe Belfiore also showed off a new notifications bar as well as the Continuum feature, which enables users to seamlessly switch between tablet and PC mode.
"A device like this elegantly transforms from one mode to another," he said, demonstrating how a Surface tablet changed as it was connected and disconnected from a keyboard.
Mr Belfiore also revealed Microsoft's digital assistant, Cortana, is coming to desktop computers for the first time. It means the voice-based assistant will now run on Windows PCs, and can be used to assist with tasks.
Cortana can be used to ask questions as well as look up information from the web, via voice command. The software is similar to the Siri software that runs on Apple devices, however this is the first time such an assistant has come to desktop devices.
"Having Cortana on your PC is like having another member of the family sitting around and helping you get things done," said Mr Belfiore.
The software is also capable of learning the user's habits, as well as launch apps on command. Users will be able to play music, but when you say "Hey Cortana, please be quiet", the music will pause.
The system also has the ability to dictate and send emails.
"This capability will be rolling out to insiders over the next several months," Mr Belfiore added.
Mr Belfiore also demonstrated how Windows 10 will work on smartphone and tablets. "We're tailoring it ... for certain form factors. What I'm going to show you now is the Windows 10 version that is tailored for devices that are smaller than eight inches," he said.
The Microsoft executive then used a Lumia tablet to show the mobile version of Windows 10. Notifications have now been linked between mobile devices and desktop, so dismissing a notification on mobile will also remove it from your PC.
The keyboard can also now be floated anywhere around the screen so users can place it where it is most comfortable for them. The messaging and Skype apps are also set to be synced together, so users can jump between the two programs seamlessly as they chat to contacts. Voice-dictated messaging was also demonstrated on-stage.
Microsoft's signature productivity apps - Office, made up of Word, Excel and PowerPoint - will all be built into Windows 10 on smartphones. Outlook, Microsoft's email system, is also included. In a new feature, Word has been built into the universal email app for the first time, which Microsoft hope will make message composition easier.
These formed part of a demonstration of a host of Windows apps that Microsoft used to show off how their native apps are now all universal - and will work no matter which Windows device a user is working on.
Microsoft's native Photos app has also been updated so that it is now powered by the cloud - where a user's computer and phone will work together to create collections of photos and albums.
This moves it close to Apple's iCloud-driven photo set-up.
A wide-spread rumour ahead of the launch was based around whether or not Microsoft would introduce a new web browser.
"We think it's the right time to build a new browser for the modern web," Mr Belfiore said.
"I'm excited to introduce you to ... codename Project Spartan," before adding that it was still an unfinished product.
Mr Belfiore focused on three key features for Spartan, the first of which was a note-taking mode which enabled users to write and draw on the page with a stylus before sharing it complete with your added notes to social media and other outlets like email.
The second feature is reading-based, with Microsoft introducing an option where users could change the appearance of a webpage so that it looked like a book.
There was also a reading list where users could save articles and pages for later.
Again, the move was similar to features on Apple's iOS - a similar reading mode and list are both available on iPad, with reading lists also available on Macs.
Microsoft also confirmed that Cortana would be built into Spartan and would offer directions when you visited a restaurant's site, as well as tell you about the menu and give dietary information once prompted.
Mr Belfiore confirmed it would be "three, four, five months" before those on the firm's preview program would be able to start using Spartan.
The head of Microsoft's hugely successful games console Xbox, Phil Spencer, also appeared at the demo.
He confirmed that the official Xbox app would now be built into every Windows 10 device.
"Gaming on Windows 10 will be more social and interactive," he said.
Players will be able to interact with friends as well as capture and share clips of up 30 seconds from within your game.
"Bringing more power to Windows 10 gaming is incredibly important to us," he said.
Gamers will now also be able to play across different platforms in Windows 10, and on-stage Mr Spencer played Fable Legends with Lauren Carter from developer Lionhead studios, with Mr Spencer on a PC and Miss Carter on the Xbox One.
Mr Spencer also confirmed that console exclusive games not currently available on Windows could now be played anywhere.
"With Windows 10, we will enable streaming of Xbox One games to any Windows 10 PC or tablet in your home later this year," he added.
Mr Myerson confirmed that the new version of Windows 10 will be available to those in the Insiders preview program from next week, with a version for phones coming in February.
"After the Seahawks win the Super Bowl, we'll be releasing our first build of Windows 10 on phones," he said. "We're looking forward to feedback from insiders all over the world."
As well as software, Microsoft also introduced a new device; the Microsoft Surface Hub - an 84-inch touch display that works similarly to a tablet.
The screen comes with dual cameras so it can be used as a display which can be used to give presentations, and it has built-in dual cameras so it can also be used as part of interactive video conferencing, with edits on-screen appearing live for all those in the session. Microsoft call it Ink Back and Touch Back.
A new holographic technology was also introduced, of which Mr Myerson said: "In my decades in this industry there have been a few key moments where a technology has blown me away. We've created one of those experiences with Windows 10."
Alex Kipman, who previously worked on the Xbox Kinect motion sensor camera unveiled Windows Holographic and HoloLens, a virtual reality headset which enables users to see and interact with holograms that appear around them. A demonstration video showed people wearing the headset and viewing Skype calls on a wall of their home, as well as games filling their living room.
"New ways to communicate, new ways to create - that's the dream we've been pursuing. Imagine an architect walking around their designs while clients are reviewing it remotely," said Mr Kipman.
"We invented the most advanced holographic computer the world has ever seen."
The HoloLens headset works without any connection to a PC or any wires.
"HoloLens has see-through, holographic lenses", said Mr Kipman.
The device enables users to draw in the air, working on holograms of programs that appear through the headset. The device knows where you are looking and responds to gestures and voice commands. Users can even create objects as holograms and then 3D print them to physically create them using a new suite called Holo Studio.
Virtual reality headsets such as the Oculus Rift and Samsung Gear VR are becoming increasingly popular and usable, and now Microsoft has entered the marketplace for the first time. Microsoft also revealed that the technology giant has worked with Nasa on its hologram technology, including with the Mars Curiosity Rover.
Microsoft chief executive Satya Nadella also took to the stage at the end of the presentation to sum up what the company had just unveiled.
"What an incredible moment. These are the kind of magical moments that we live for," he said.
" What you just saw in terms of the experiences ... you're going to play Minecraft, you're going to see Skype in a completely new way. They're just going to be mind-blowing experiences. Today is a big day for Windows, a big day for what it means for our customers, our partners, and for Microsoft.
"Most of all, it's about new opportunities. The fact that there are 1.5 billion users of Windows is incredible and humbling. It's a responsibility that none of us at Microsoft take lightly. We want to move from people needing Windows, to choosing Windows and loving Windows. That is our bold goal with Windows.
"Windows 10 is built for a world where there are going to be more devices on the planet than people. It ushers in an era of more personal computing in a mobile-first, cloud-first world.
"When it comes to Windows as a service, it's a pretty profound change. We want people to love Windows on a daily basis."
Mr Nadella, who has been head of the technology giant for almost a year also summed up the new cross-platform experience shown in Windows 10.
"Simply put, Windows is the best place. It's the home for the very best Microsoft experiences," he said.
"We absolutely are going to have our services and applications everywhere, but we absolutely believe that Windows is home for the very best of Microsoft experiences.
"We are really looking forward to how our Windows insiders use the new builds of Windows, and the feedback from that is very important. We want to make Windows 10 the most loved release of Windows."
Mr Myerson then signed off the show by saying that Windows 10 will arrive "later in the year", though did not specify a launch date.