Those needing evidence of the radical changes underway at Microsoft needn't look any further than today's news. The Redmond-based company on Thursday announced that its Office suite of apps - Word, Excel and PowerPoint - are now available free of charge on Android and iOS devices.

Office is one of Microsoft's oldest and most successful products ever. Originally launched in 1990, the suite of apps accounted for nearly a third of Microsoft's revenue - or around $26 billion - during the last fiscal year.

Considering how important Office is for Microsoft's bottom line, it initially seems crazy to simply give the software away for free to mobile users. But as Microsoft head of Office marketing Michael Atalla explains, it's not a total strategic shift but rather an extension of their existing strategy.

That makes sense when you consider Microsoft already offers free Office apps online. Essentially, they're taking the same user experience provided online and bringing it to native apps for Android and iOS. The goal, Atalla said, is to make sure customers can be productive across all the devices they have.

It's worth pointing out that Microsoft is only extending the offer to individual users. Businesses will still be required to have an Office 365 subscription to edit documents, we're told.

What's more, Microsoft has launched the start of their Office for Android tablet Preview. Those interested in the Android Preview will need to be using an Android tablet with a screen size between 7 inches and 10.1 inches running KitKat. Interestingly enough, Microsoft isn't looking for tablets running Lollipop at this time.