Microsoft has been expanding the number of different ways it can update Windows components for a while now. Today, October 14, officials announced they're beginning to test yet another vehicle for this, which they've christened "Update Stack Packages."
Microsoft introduced Update Stack Packages as part of the announcement of a new Windows 11 build for the Dev Channel. That build, Windows 11 build 22478, includes a number of fixes plus new emoji built using the Fluent design language. Today's test build also allows users to log into their PCs using facial recognition via Windows Hello on an external monitor if that monitor has a camera attached that supports it. For the full list of fixes and updates in today's build, check the blog post.
But back to Update Stack Packages. Details are a bit scarce at the moment.
Microsoft officials said these packages will "deliver update improvements outside of major OS updates, such as new builds." Through an Update Stack Package, Microsoft officials said they'll be able to deliver improvements to the update process before a PC actually takes a monthly or a feature update.
Currently, the Update Stack Package "is limited to a very small set of update-related system files that are developed independently of the OS," officials said. Microsoft hopes to be able to expand the scope and frequency of Update Stack Package releases in the future.
"The Update Stack Package will help ensure that your PC has the highest likelihood of successfully installing new updates with the best and least disruptive experience available," today's blog post said. These packages will be delivered to Insiders through Windows Update, just like builds and cumulative updates are today.
Starting with build 22478, Insider testers can opt to receive the Update Stack Packages by going to Settings > Windows Update and checking for updates.
I'm not sure exactly how (and if) the new Update Stack Package fits in with the existing Windows servicing stack updates. (I've got a question in to Microsoft on this.)
Servicing stack updates provide fixes to the servicing stack, which is the component that installs Windows updates. Servicing stack updates also contain the component-based servicing stack (CBS), "which is a key underlying component for several elements of Windows deployment, such as DISM, SFC, changing Windows features or roles, and repairing components," according to Microsoft's documentation.
Starting in February 2021, Microsoft made it so new cumulative updates for Windows 10 (and now, 11) would include the latest servicing stack updates, in the name of providing as a "single cumulative update payload" to both Windows Server Update Services (WSUS) and the Microsoft Catalog. when using endpoint management tools with WSUS, such as Configuration Manager, users could simply select and deploy the monthly cumulative update.