Microsoft is now testing Windows 10 build 17688 internally. The new Windows 10 Redstone 5 build 17688 (10.0.17688.1000 rs_prerelease.180605-1530) was compiled on June 5, 2018.
Recently, Windows 10 Redstone 5 build 17686 was released for Fast and Skip ahead Insiders. According to the official changelog, the latest insider build comes with a new Region page that allows overrides to default regional format settings such as Calendar, First day of the week, Dates, Times, and Currency. The new build also includes a new privacy and Windows Mixed Reality improvements.
Windows 10 April 2018 Update is also now available for end users. The latest major update comes with new features like Timeline, Focus Assist and more. Apart from this, it includes various changes and improvements. You can download the ISO files from the link below.