[[Microsoft]] was one of the first companies to implement [[Unicode]] in their products. [[Windows NT]] was the first operating system that used "wide characters" in [[system call]]s. Using the (now obsolete) [[UCS-2]] encoding scheme at first, it was upgraded to the [[variable-width encoding]] [[UTF-16]] starting with [[Windows 2000]], allowing a representation of additional planes with surrogate pairs. However Microsoft did not support [[UTF-8]] in its API until May 2019.
Before 2019, Microsoft emphasized UTF-16 (i.e. -W API), but has since recommended to use [[UTF-8]] for programs (at least in some cases),<ref name="Microsoft-UTF-8" /> on Windows and [[Xbox]] (and in other of its products), even states "UTF-8 is the universal code page for internationalization [and] UTF-16 [..] a unique burden that Windows places on code that targets multiple platforms. [..] Windows [is] moving forward to support UTF-8 to remove this unique burden [resulting in] in fewer internationalization issues in apps and games".<ref>{{Cite web |title=UTF-8 support in the Microsoft Game Development Kit (GDK) - Microsoft Game Development Kit |url=https://learn.microsoft.com/en-us/gaming/gdk/_content/gc/system/overviews/utf-8 |access-date=2023-03-05 |website=learn.microsoft.com |language=en-us |quote=By operating in UTF-8, you can ensure maximum compatibility [..] Windows operates natively in UTF-16 (or WCHAR), which requires code page conversions by using MultiByteToWideChar and WideCharToMultiByte. This is a unique burden that Windows places on code that targets multiple platforms. [..] The Microsoft Game Development Kit (GDK) and Windows in general are moving forward to support UTF-8 to remove this unique burden of Windows on code targeting or interchanging with multiple platforms and the web. Also, this results in fewer internationalization issues in apps and games and reduces the test matrix that's required to get it right.}}</ref>
A large amount of Microsoft documentation uses the word "Unicode" to refer explicitly to the UTF-16 encoding. Anything else, including UTF-8, is not "Unicode" in Microsoft's outdated language (while UTF-8 and UTF-16 are both Unicode according to the [[Unicode|the Unicode standardStandard]], or encodings/"transformation formats" of).
