Windows as a service

Windows as a service is the development model Microsoft has adopted for Microsoft Windows after the release of Windows 10. Instead of releasing a major version of Windows every few years, the company instead releases smaller feature updates in shorter intervals.

Since Windows transitioned to Azure's semester model in 2019, new features are planned with respect to the so-called semesters rather than feature updates. From a development viewpoint, semesters are equivalent to releases as the active development branch goes through feature development, stabilization and sign-off phases during each semester. However, they are independent from the actual releases available to the public as the company does not necessarily release a new version at the end of each semester, e.g. three semesters passed between Windows 11 and Windows 10 May 2020 Update (Manganese, Iron, Cobalt).

Recent rumors suggest that Microsoft might be moving back to a traditional release schedule, with a major version of Windows releasing every three years. The period between two major versions would then be spanned by shipping minor feature updates called Moments, up to four times a year.

List of development semesters

Name	Abbr.	Semester	Rel. branches	Release				Notes
				Client	Server	AzSHCI	Xbox
Threshold 1	TH1	—	Yes	Windows 10	—	—	—	—
Threshold 2	TH2	—	Yes	Windows 10 November Update	—	—	v1510	—
Redstone 1	RS1	—	Yes	Windows 10 Anniversary Update	Windows Server 2016	—	v1608	—
Redstone 2	RS2	—	Yes	Windows 10 Creators Update	—	—	v1704	—
Redstone 3	RS3	—	Yes	Windows 10 Fall Creators Update	v1709	—	v1710	—
Redstone 4	RS4	—	Yes	Windows 10 April 2018 Update	v1803	—	v1804	—
Redstone 5	RS5	—	Yes	Windows 10 October 2018 Update	Windows Server 2019 v1809	v20H2	v1810	—
Titanium	Ti	19H1	Yes	Windows 10 May 2019 Update	v1903	—	v1904	First iteration under the Azure semester scheme
Vanadium	V	19H2	Partial	Windows 10 November 2019 Update	v1909	—	v1910	Cumulative update for 19H1 (Titanium)
Vibranium	Vb	20H1	Yes	Windows 10 May 2020 Update Windows 10 October 2020 Update Windows 10 May 2021 Update Windows 10 November 2021 Update Windows 10 2022 Update	v2004 v20H2	—	v2004	Named after the Marvel Comics element instead of continuing the line of chemical elements with Chromium in order to prevent confusion with the web browser project.
Manganese	Mn	20H2	Yes	—	—	—	—	—
Iron	Fe	21H1	Yes	—	Windows Server 2022	v21H2 v22H2	—	—
Cobalt	Co	21H2	Yes	Windows 11	—	—	v2108	—
Nickel	Ni	22H2	Yes	Windows 11 2022 Update Windows 11 2023 Update	—	—	v2208	Originally 22H1, later changed to 22H2 and expanded to cover the entire year.
Copper	Cu	23H1	No	—	—	—	—	—
Zinc	Zn	23H2	Yes	—	v23H2	v23H2	v2308	—
Gallium	Ga	24H1	No	—	—	—	—	—
Germanium	Ge	24H2	Yes	Windows 11 2024 Update	Windows Server 2025 v24H2	v24H2	v2408	—
Dilithium	Dt	25H1	No	—	—	—	—	Named after the Star Trek element instead of continuing the line of chemical elements with Arsenic because of its negative associations.
Selenium	Se	25H2	TBA	TBA	TBA	TBA	TBA	—