A new release model called Windows as a service was introduced with smaller and regular feature updates, as opposed to releasing a major version of Windows every few years. Usually, these updates are a new build of the operating system, although in a few cases Microsoft released feature updates consisting of a limited set of new functionality using the regular cumulative update infrastructure. From 2017 to 2021, feature updates were released twice in a year, with the first feature update being released in spring and the other in fall. The schedule was realigned in 2021 in that feature updates for Windows 10 would be released annually in order to be consistent with Windows 11's new release cadence.[3]