Microsoft has announced that there will be two primary release channels available to Windows Server customers, the current long-term channel (option) and a new semi-annual channel (option).
New Semi-annual Channel
The Semi-annual Channel releases will deliver new functionality for customers who are moving at a “cloud cadence," such as those on rapid development cycles or hosters keeping up with the latest Hyper-V investments.
The new semi-annual Windows Server release model is consistent with the similar release and servicing models for Windows 10 and Office 365 ProPlus.
Windows Server products in the Semi-annual Channel will have new releases available twice a year, in spring and fall. Each release in this channel will be supported for 18 months from the initial release.
Most of the features introduced in the Semi-annual Channel will be rolled up into the next Long-term Servicing Channel release of Windows Server. The editions, functionality, and supporting content might vary from release to release depending on customer feedback.
The Semi-annual Channel will be available to volume-licensed customers with Software Assurance, as well as via the Azure Marketplace or other cloud/hosting service providers and loyalty programs such as MSDN.
Long-term Channel
This is the release model that most Windows Server customers are already familiar with (currently called the “Long-term Servicing Branch”) where a new major version of Windows Server is released every 2-3 years. Users are entitled to 5 years of mainstream support, 5 years of extended support, and optionally 6 more years with Premium Assurance. This channel is appropriate for systems that require a longer servicing option and functional stability.
Microsoft said that, deployments of Windows Server 2016 and earlier versions of Windows Server will not be affected by the new Semi-annual Channel releases. The Long-term Servicing Channel will continue to receive security and non-security updates, but it will not receive the new features and functionality.
Microsoft
MS Server Release Channel Changes
In this new model, Windows Server releases are identified by the year and month of release: for example, in 2017, a release in the 9th month (September) would be identified as version 1709. Windows Server will release semi-annually in fall and spring. Another release in March 2018 would be version 1803. The support lifecycle for each release is 18 months.
For more details, including Device compatibility, Servicing, and more see the article titled, Windows Server Semi-annual Channel Overview in the Microsoft Windows IT Center.
Content adapted or mirrored from the above referenced article.