https://wccftech.com/redstone-5-windows-10-1809/

Microsoft has today released a new build of Windows 10 Redstone 5 to Insiders on the Fast Ring bringing several improvements and bug fixes. The Redmond software maker is already done with testing new features for the upcoming version of its desktop operating system and is currently focusing on performance improvements and stability.

Along with the usual bug fixes, today’s build also introduces the official version number to the Preview Build, confirming that the next Windows version is to be Windows 10 1809 (via Neowin). The first two digits of this version number correspond to the year while the last two reveal the month of release of a particular Windows version (usually its RTM build) to the public.