With the release of Windows 10 (version 1903) in May 2019, a new updated, fully-fledged Narrator screen reader was included as part of the release. Narrator was designed to open up accessibility as a screen reader for visually impaired users, but sadly lacked the power and features of its contemporaries such as JAWS and the now-defunct Windows Eyes.
Windows Narrator has been a Windows accessibility feature as far back as Windows 2000.