Microsoft has today launched the first update to Windows Phone 8.1, known as GDR1 or simply 'Update 1', with users in the Preview for Developers program set to get the update over-the-air some time this week.

Update 1 is a relatively minor update compared to Windows Phone 8.1 itself, which launched earlier this year. The main new feature is Live Folders, which allows you to group apps in folders on the Windows Phone homescreen, and still receive notifications through Live Tiles.

Other new features include improvements to Xbox Music, SMS merge and forwarding functionality, proper support for VPNs, support for quick charging standards such as Qualcomm Quick Charge 2.0, and the Apps Corner. Similar to the Kid's Corner, you can select apps to go in the Apps Corner so that when you hand your phone to someone else, personal data isn't exposed.

Alongside the launch of Windows Phone 8.1 Update 1, Microsoft has announced that Cortana - Windows Phone's voice-controlled personal assistant - is now available for users in China and the United Kingdom. An alpha version will also be available for those in Canada, Australia and India on an opt-in basis.

If you want to update your Windows Phone to Windows Phone 8.1 Update 1, for now you'll need to sign up for the free Preview for Developers program. Manufacturers will formally push the update to existing devices in the coming months.