Microsoft launches Office 2013 software suite

Microsoft has launched a new version of its Office software suite.

Word, Excel, Powerpoint and Outlook have been redesigned to work better with touch-screen-controlled computers.

They also integrate the firm's Skype video chat facility. Users can add further functions via a new app store.

The programs account for a major part of Microsoft's earnings. The firm hopes to keep users loyal by offering more powerful features than cheaper online alternatives.