A new Windows 10 insider build v18305 improves security, features, and fixes bugs for the 19H1 release later this year.  Venture Beat highlights in excellent detail.

Microsoft releases new Windows 10 preview with security, Narrator, and accessibility improvements

Microsoft today released a new Windows 10 preview with improvements to security, the Narrator app, and accessibility. The update bumps Windows 10 from build 18305 (made available to testers on December 19) to build 18309. These builds are from the 19H1 branch, which will arrive in the first half of this year. Windows 10 is being developed as a service, meaning it receives new features on a regular basis. Microsoft has released six major updates so far: November Update, Anniversary Update, Creators Update, Fall Creators Update, April 2018 Update, and October 2018 Update.