Formal releases provide a stable, supported platform for use in production systems. They are also the proper choice for starters and for everyone who wants to get to know NetBSD. The latest formal release is NetBSD 9.1 (release information).
More information about the NetBSD releases:
The following releases are currently supported. This means that they receive bug fixes. Anything older then the releases below are no longer supported and will not receive any bug fixes, including security fixes. Any changes made to the releases below will be included in the next release of the same series when and if one is made. That is, changes made to NetBSD 8.2 will appear in 8.3 and changes made to NetBSD 9.0 will appear in NetBSD 9.1.
The NetBSD 9.x series:
The NetBSD 8.x series:
NetBSD-current is the development version of NetBSD. Builds of -current generally provide more features than formal releases, but have not had the same degree of testing, and should be avoided on production systems where possible. They are aimed at developers, experienced testers, and early adopters. More information is available at the NetBSD-current page.