Apple has released the fourth beta version of macOS Big Sur 11 to users who are participating in the Big Sur beta testing program.
Usually a developer version rolls out first and is soon followed by a public beta release, but in this case the public beta of macOS Big Sur is yet to be released.
Separately, Apple also released iOS 14 beta 4 and iPadOS 14 beta 4, along with tvOS 14 beta 4 and watchOS 7 beta 4.
MacOS Big Sur features a redesigned user interface with a more iOS-inspired design, the addition of Control Center for the Mac, new Messages app features that bring it more in line with the version on iPhone and iPad, instant language translation for webpages within Safari, along with a variety of other features and changes.