All Windows administrators and many Windows users know that Microsoft releases updates on the second Tuesday of any month for all supported operating systems.

Microsoft's John Wilcox published information about the Windows 10 update servicing cadence yesterday on the company's Tech Community website.

He shares Microsoft's guiding principles for updates for Windows 10, and provides context to help users and administrators better understand when and how updates do get released.

Update Tuesday, or Patch Tuesday, is the most important day of the month when it comes to updates. Microsoft refers to quality updates that it releases on the day as "B" releases.

The updates released on the second Tuesday of each month are "the primary and most important of all the monthly update events and are the only regular releases that include new security fixes".

Why Tuesday was selected by Microsoft

you may have asked yourself why Microsoft releases updates on the second Tuesday of each month at 10:00 a.m. Pacific time. The day and time was selected intentionally for two reasons:

• To give administrators time to deal with other things on the first day of the week (Monday).
• To give admins enough time to deal with issues that may be caused by update installations (Wednesday to Friday).

Update Tuesday was formalized in October 2003 by Microsoft. The company releases updates when they were ready prior to that month; while that pushed out updates as early as possible, it meant that administrators had to work more to test and deploy updates as they were not released on schedule.

Microsoft may release "C" or "D" releases on the third or fourth week of each month besides that. These are preview releases that contain no security updates but only non-security updates.

The main intention of these updates is to provide system administrators and home users with options to test these updates before they are made available on the upcoming month's Patch Tuesday.

Microsoft pushes out previews most commonly as "D" releases two weeks after Patch Tuesday ("B" releases" and two weeks before the coming month's Patch Tuesday.

The company may release updates for older versions of Windows 10, and for Windows 7 and 8.1, a week early as "C" releases instead to extend the test period to three weeks.

Preview releases for the most recent versions of Windows 10 may also be shifted to the "C" releases week when the release of a new feature update draws closer as fewer time for testing is required.

Microsoft may release out-of-band releases also. These updates follow no schedule and are reserved for updates that resolve issues that require immediate updating; common scenarios include patches for vulnerabilities that are widespread and exploited in the wild or fixes for issues that impact functionality or stability.

The company has three guiding principles for monthly quality update releases on Windows 10:

• Be simple and predictable -- Updates are released on schedule (with the exception of out-of-band updates) so that administrators and users can play ahead and test releases before deployment.
• Be agile -- provide updates quickly when required, and without compromising quality or compatibility.
• Be transparent -- offer as much information as needed to prepare, test, and deploy updates. Provide simple release notes, servicing tools, and more.

Closing Words

It is certainly helpful that Microsoft releases updates on schedule as it allows administrators to test releases and prepare for them. Microsoft's guiding principles are noble ones but the company does not always do them justice.

It happens that Microsoft releases KB support pages after updates become available on Windows Update so that users and admins can't really find out what an update is about right away.

If you take that into account and the fact that it is difficult to block updates on Windows 10, it should not come as a surprise that third-party solution to block updates such as Windows 10 Update Switch or Windows 10 Updates Disabler have been created.

The quality of updates seems to have suffered in recent time as well.

@Xanadu, nice news. It's actually very interesting to know the cadence.