Microsoft's much anticipated 8.1 release to its Windows operating system is being rolled out from today.

The update to the heavily criticised Windows 8 will be offered free via the Windows Store in over 230 markets and 37 languages to anyone with a device running the latest operating system.

The update will also be available on new products and as boxed software from retailers, starting tomorrow. The Irish language pack, however, will not be available immediately.

The download aims to correct some of the features of the Windows 8 Operating System (OS), that attracted criticism upon its release.

The familiar Start button, which had been a recognised part of Windows systems in the past, has been brought back in 8.1.

Users can also set the system to boot up their machine straight to Desktop view, instead of the default tile interface that was introduced in Windows 8. The Start screen can also be customised to offer variable tile sizes, as well as more background designs and colours.

The Apps view has also been updated, to allow users see all their apps at once. Microsoft claims it has also improved the search function.

The OS will also provide native support for 3-D printing, while the Windows Store has been redesigned.

With a tile based interface, Windows 8 had aimed to bring together PC, tablet and mobile operating systems into one uniform recognisable style.

But the original release attracted much criticism for its at times non-intuitive interface, which was arguably more suited to touch screen devices than traditional laptop and PC use.

As a consequence, sales of Windows 8 machines disappointed, not helped by an overall global decline in shipments of traditional PCs. The update comes as Microsoft seeks a new boss, following the announcement by Steve Ballmer that he is stepping down next year.