Windows 8 was released with four editions, with varying feature sets. The editions with modified features are called Pro, Enterprise, and RT. There are versions of these that features modified for legal or marketing reasons.
Unlike Windows Vista and Windows 7, there are no Starter, Home Basic, Home Premium, or Ultimate editions.
All mentioned editions have the ability to use language packs, enabling multiple user interface languages. (This functionality was previously only available in Windows 7 Ultimate or Enterprise.) However, in China and other emerging markets, a variation of Windows 8 without this capability, called Windows 8 Single Language, is sold. This edition can be upgraded to Windows 8 Pro.
Additional Windows 8 editions specially destined for European markets have the letter "N" (e.g. Windows 8.1 Enterprise N) suffixed to their names and do not include a bundled copy of Windows Media Player. Microsoft was required to create the "N" editions of Windows after the European Commission ruled in 2004 that it needed to provide a copy of Windows without Windows Media Player tied in.
Windows 8.1 with Bing is a reduced-cost SKU of Windows 8.1 for OEMs that was introduced in May 2014. It was introduced as part of an effort to encourage the production of low-cost devices, whilst "driving end-user usage of Microsoft Services such as Bing and OneDrive". It is subsidized by Microsoft's Bing search engine, which is set as the default within Internet Explorer, and cannot be changed to a third-party alternative by the OEM. This restriction does not apply to end-users, who can still change the default search engine freely after installation. It is otherwise identical to the base edition.
The following in-place upgrade paths are supported from Windows 7. Note that it is only possible to upgrade from an IA-32 version of Windows 7 to an IA-32 version of Windows 8; an x64 version of Windows 7 can only be upgraded to an x64 version of Windows 8. The retail package entitled Windows 8 Pro Upgrade was restricted to upgrading a computer with licensed Windows XP SP3, Windows Vista or Windows 7. Finally, there is no upgrade path for Windows RT, as it is the only version of Windows that currently supports the ARM architecture.