Windows Update (WU)
Definition - What does Windows Update (WU) mean?
Techopedia explains Windows Update (WU)
Depending on the settings, Windows Update can deliver security updates, service packs and critical updates. Again, Windows Update can be configured to perform either an automatic installation or a manual installation, although important updates are usually recommended for automatic installation. Optional updates are the only updates installed manually. Windows Update provides an update history, which can be viewed by the user to determine what has been installed and the time of update. Troubleshooting assistance is also provided for failed Windows updates.
To perform its task, Windows Update requires the Internet Explorer Web browser because it uses ActiveX controls to modify the software used in the computer. Installed updates can be removed manually, but this action is recommended only when a particular update is found to be causing issues.