Microsoft is set to give more details on its virtual reality computing headset HoloLens.

Despite a slow start that left show viewers struggling to keep up with the technical content, Microsoft has been showing off new features in its Office software.

At the firm's developer conference, Build, in San Francisco, the first hour of the live show was dedicated to the firm's Azure cloud platform, complete with several coding demonstrations.

But once Microsoft's Rob Lefferts appeared on stage to speak about Office, a new ability to see Office add-ins across Windows, the web and Apple's iOS was demonstrated.

A link between Microsoft email and calendar service Outlook and Uber was also shown off, where the car-sharing app was able to learn a user's destination from an Outlook meeting reminder.

"You're no longer going to different applications for different data," said Mr Lefferts.

Microsoft chief Satya Nadella opened the conference, aimed at developers, by saying: "This conference is all about celebrating and challenging the creativity that you all bring.

"Microsoft was founded by two developers who had a bold ambition to empower other developers to build new and great things."

Microsoft also announced a new code editor, Visual Studio Code, that will enable developers to edit code on the Mac and Linux platforms for the first time for free.

The US firm is looking to improve its standing in the technology market place after falling behind to the likes of Apple and Google in recent years both in terms of sales and popularity.

Mr Nadella then returned to the stage.

"I know you all waited very patiently to hear about Windows, and it's now time to talk about Windows," he said to cheers from the crowd.

"Windows 10 is not just another release of Windows, it's a new generation of Windows. It is a very different Windows in terms of how we deliver it. It's a service.

"I'm really excited about where we are in this journey, but I'm most excited about what we together are going to do in the coming year with Windows 10."

Terry Myserson, the head of Windows, took to the stage to discuss the new features of Windows 10, which Microsoft first previewed earlier this year.

"Our goal is to make Windows 10 the most attractive development platform ever," he said.

"From devices with small screens like phones to large screens, going beyond and all-in-one PC to large wall-mounted displays like Surface Hub. We're talking about one platform, a single app, a single binary that can run across all of these devices."

Windows 10 is set to let consumers use apps across any devices, including smartphones and even the Xbox One. Mr Myerson was quick to point out that some rivals do not allow such freedom.

"With Apple you choose to invest in iOS and OS X. With Google it's Android or Chrome OS. Windows is the only platform that lets you bring apps to all these devices efficiently."

Microsoft also announced that Windows was introducing something called "carrier billing", which will enable users to buy apps and services through their phones instead of using a credit card.

Mr Myerson added that the company's aim was to have one billion devices running Windows 10 within "two to three years".

The Windows 10 aim of making all apps universal was also demonstrated, with the USA Today app shown being used across a range of devices with different screen sizes; automatically optimising and resizing as the app was used on different devices, from desktop computers to smartphone.

Windows 10 will also begin to recognise and display some websites as apps. The DJ website 22Tracks was shown as an example - with the website registered with the Windows App Store. When Windows 10 users visit the 22Tracks website, and others, it will appear as an app rather than a web page. Mr Myerson said this will give more developers access to app versions of their products more easily.

The rumour that Android apps will become compatible with Windows 10 was also confirmed. Mr Myerson said the code used to run apps on Android will be now reusable on Windows.

"To make this possible, Windows Phones will include an Android subsystem," he said.

Microsoft also announced something called Objective C, which will enable developers to convert code from Apple iOS apps via Microsoft's new Visual Studio and then run the apps on Windows.

The announcement drew several large cheers and rounds of applause from the developer-centric audience.

Mr Myerson added that this system was how Candy Crush Saga has been introduced to Windows.

Joe Belfiore then took to the stage to explain more about Windows 10.

This included how Microsoft is bringing back the much-loved Start menu, as well as a more personalised lock screen which learns how a user works with their PC, and displays prompts and questions on screen based on what you have and haven't used.

Microsoft calls it the Windows Spotlight, and Mr Belfiore said it is in place to help users "find and discover value in the Windows ecosystem".

The firm's virtual personal assistant, Cortana, also made an appearance. This included the ability to tell the assistant to do something from specific apps such as telling it to use certain apps to send messages.

Microsoft also finally confirmed the name of its new web browser - Microsoft Edge. Until now, the new browser has been known as Project Spartan.

"For us, it refers to being on the edge of consuming and creating," said Mr Belfiore. "It's a browser that end users will think about for getting things done."

The new browser is set to replace the much-maligned Internet Explorer in Windows 10. It will have Cortana built in and will "learn" how users browse the web. Extensions, including for social media sites like Pinterest, will also now be built into Edge, with dedicated buttons now appearing in the tab bar.

The Continuum feature, which gives users the power to put one device down running an app, and then pick it up in exactly the same place on another, was also demonstrated, with the feature working on smartphone for the first time. This will enable users to turn their phone into a PC, with the larger screen becoming the monitor.

"With Continuum, we believe any screen can be your PC," said Mr Belfiore. "Imagine you're on vacation and your hotel room can become a theatre, or you connect your phone to a TV screen.

"What we're trying to show here today, is our unique vision for phones and enabling them to scale up to a full PC-like experience."

Microsoft's Alex Kipman, the face of the HoloLens headset, then took to the stage.

"Less than 100 days ago we showed you how Windows Holographic amplifies what's human about all of us. We introduced Microsoft HoloLens."

Mr Kipman and a volunteer showed off the Windows Holographic platform for the first time, and showed how users can create a custom "space" for themselves - a virtual home - where all their apps are stored. The demo on-stage was modelled on a Microsoft employee's own apartment. The Skype app, and a video player were shown off as available apps.

Saying "follow me" will see the holograms follow you as you move around too, so users can take their media with them, and scale the tile size to suit you. The audience saw a video follow the volunteer - Darren - as he moved around.

A video then demonstrated how architects can collaborate using the HoloLens headset, and even walk around the plans they are working on.

Microsoft also announced a new partnership with a university, and showed how HoloLens is being used to teach medical students anatomy. The headset enables students to see different parts of the body in more detail than previously possible, and in 3D. Partnerships are also in place with Nasa and Disney.

The technology firm also reiterated that HoloLens will be untethered; not needing to be paired to any other device in order to work.

HoloLens will also work with the Internet of Things, and this was demonstrated by a voice-controlled physical robot that appeared on stage, that then had a holographic robot projected on top of it. This was then controlled and customised using holographic control panels the HoloLens wearer can see. The robot was able to move and be aware of its surroundings because the headset scans the environment.

Mr Nadella returned to the stage to sign off the keynote, saying that it was Microsoft's ambition to move users from choosing Windows to "wanting" the software. However the Microsoft chief did not confirm any release dates for Windows 10 or the HoloLens headset.

The Microsoft Build conference will now turn into a series of seminars, and runs until Friday.