Windows 10 released as free upgrade

Microsoft has released Windows 10, the latest version of its operating system, as a free upgrade for hundreds of millions of existing users.

The software was launched on 29 July in 190 countries. People with Windows 7 or Windows 8.1 can upgrade free of charge for the first year.

A fresh start

Windows 10 follows Windows 8, released in 2012, which was criticised for its design. Windows 8 replaced the familiar Start menu with a screen of tiles designed for touch screens, and many users found it confusing on traditional computers with a keyboard and mouse.

Windows 10 brings back the Start menu, combined with some of the tiles from Windows 8. It is designed to work on desktop computers, laptops, tablets and phones.

Microsoft skipped the name Windows 9 altogether, saying the new version represents such a big change that it deserved a new number.

New features

The new system includes a digital assistant called Cortana, which responds to voice commands, and a new web browser called Edge, replacing Internet Explorer as the default.

It also includes features for gaming, including the ability to stream games from the Xbox One console to a Windows computer.

Windows as a service

Microsoft says Windows 10 will be the last major version of the operating system. Instead of releasing new versions every few years, the company will update Windows 10 regularly with new features and security fixes.

Updates will be installed automatically for home users, which has raised some concern among users who want more control over their computers.

Privacy concerns

Privacy campaigners have raised questions about the amount of information Windows 10 collects about how people use their computers. Microsoft says the data helps improve its services and that users can change their privacy settings.

A changing market

Windows is used on the vast majority of the world's desktop and laptop computers, but Microsoft has struggled to compete in the smartphone and tablet markets, which are dominated by Apple and Google.

Sales of personal computers have been falling as more people use phones and tablets to go online.

Microsoft's chief executive, Satya Nadella, who took over last year, hopes Windows 10 will help the company regain ground. The company says it wants Windows 10 to be running on a billion devices within a few years.