One of the more, seemingly, complex pieces to patching Windows computers is actually understanding the terms associated with Windows Update and the stages of update evolution. I see customers struggling to understand this constantly in the communities, so I thought a nice, quick round-up of terms would be valuable.
Once updates are released, they can enter into three different phases over time. Those phases are: Revisions, Supersedence, and Expiration.
Update Revisions: When changes are required to an update since it was released (or last published), Microsoft will label it an Update Revision. Some pieces of the download have changed. You should read through the list of revisions to determine how quickly the revised update needs to be rolled out. For example, if actual files were updated due to bugs in the original release, you may want to test and roll it out quickly. However, if only a text file or additional languages were added, you can take your time testing and deploying the updated release. This is not a full update replacement (see Superseded Updates).
Superseded Updates: A Superseded Update (or updates) is a complete replacement of a previous release, or releases. Sometimes Microsoft will wrap multiple releases into a single package, and that package replaces all similar updates before it. If you've already rolled out the single updates, you may not need the Superseded Update since it contains all of those in a single installation. Again, the KB article associated with the update will be your key to determining if it is something critical to your environment. Superseded Updates are generally more valuable when a new PC needs to be setup and configured with the latest updates.
Expired Updates: Expired Updates are just as the name suggests – Microsoft has removed the update from the list of valid updates. Expired Updates are no longer applicable in any situation and will not be detected for installation within the environment. Most times, an update is expired after it is replaced by a Superseded Update.