A rollup is simply multiple patches rolled together into a single update. These rollups will replace individual patches for these platforms. Though individual patches allowed users and admins to be selective about which patches to apply, it resulted in fragmentation, with different PCs having different sets of updates installed, Microsoft officials said.
"The new rollup model gives you fewer updates to manage, greater predictability, and higher quality updates. The outcome increases Windows operating system reliability, by eliminating update fragmentation and providing more proactive patches for known issues. Getting and staying current will also be easier with only one rollup update required. Rollups enable you to bring your systems up to date with fewer updates, and will minimize administrative overhead to install a large number of updates."
The types of patches included in these rollups are going to include both security and reliability ones. Updates for the Servicing Stack and Adobe Flash won't be included in the rollups.
The coming monthly rollups will be published to Windows Update, Windows Server Update Services (WSUS), System Center Configuration Manager (SCCM) and the Microsoft Update Catalog. (Microsoft is working to fix the Update Catalog site so it can work with any browser; currently it doesn't work with those that no longer support ActiveX.)
Each monthly rollup will supersede the previous month's rollup. The ultimate goal is for these monthly rollups to become fully cumulative, which will happen as the team adds patches released in the past, so users need only to install the latest single rollup.
According to today's post, as of October 2016 on, Windows will release a single Security-only update. This update will include only new security patches for each month, and individual patches will no longer be available. This Security update will be available from WSUS, SCCM and the Microsoft Update Catalog -- not Windows Update -- which may explain in part Microsoft's move to change the location of its security-update downloads.