Windows 8.1A major upgrade to Windows 8 introduced at the end of 2013. Code-named Windows Blue, it featured numerous changes to the Start screen such as more tile sizes, new apps, a combined local data and Web search, a rearranged Explorer file hierarchy (for the umpteenth time), and the capability of sending screen contents directly to the TV (see Miracast). The OneDrive cloud storage (formerly SkyDrive) became more integrated.
Under the covers were internal improvements, as well as support for the Resilient File System (see ReFS) and solid state technologies (see NVMe and UFS).
Preview Release - June 2013
In June 2013, Microsoft released public previews of Windows 8.1 and Windows RT 8.1. When preview users installed the official version of 8.1, they had to re-install their apps. Users who upgraded from Windows 8 to 8.1 did not. See Windows 8 and Windows 8.1 Update.