Microsoft has pushed out another PC preview version of Windows 10, with the build number of 10166, to Fast ring members of the Windows Insider program. The new version comes three weeks before Microsoft plans to launch the public version of Windows 10 on July 29.
The official Windows Blog has the details, although there are not many:
"Hi everyone, we have a new build for PCs we're releasing today to Windows Insiders in the Fast ring – Build 10166. Just like the 3 builds we released last week, this build is all about bug fixing and fit-and-finish. Be sure to keep using the Windows Feedback app to send us feedback on any problems you're hitting to help us make sure Windows 10 is awesome when we release it on July 29th!"
In other words, things are only getting faster, smoother and ready for release. Build 10162 was already fantastic so we cannot wait to try build 10166. Head to your Settings > Update and Security to grab the latest build of Windows 10 for Insiders.