These instructions work for Windows 11 through Windows 98.
The Windows Update service has changed over the years as Microsoft released new versions of Windows.
Check for and Install Updates in Windows 11
In Windows 11, Windows Update is found inSettings.

Right-hit the Start menu and chooseSettings, or search for it from the search bar.
Once it opens, selectWindows Updatefrom the left side.
To check for Windows 11 updates, selectCheck for updates.

Windows 11 checks for updates to the OS after selecting that button, but will also do so automatically.
Check for and Install Updates in Windows 10
In Windows 10, Windows Update is found withinSettings.
To get there, choose the Start menu, followed by the gear/prefs icon to the left.
In there, chooseUpdate & Securityand thenWindows Updateon the left.
Check for new Windows 10 updates by choosingCheck for updates.
Justopen Control Paneland then chooseWindows Update.
SelectCheck for updatesto check for new, uninstalled updates.
Microsoft no longer supports Windows 7, and as such, doesn’t release new updates.
Microsoft no longer supports Windows Vista, and as such, doesn’t release new updates.
Microsoft no longer supports Windows XP, nor versions of Windows that preceded it.
Another option is to use afree software updater program.
Those tools are usually built specifically for updating non-Microsoft programs but some include a feature for downloading Windows updates.
SeeHow to Change Windows Update Settingsfor more on this and how to change how updates are downloaded and installed.
FAQ
Tofix Windows update errors, initiate the Windows Update troubleshooter.
You may need to turn on the Windows Update service or disable your security software.
If Windows won’t update, use the Update Assistant on Microsoft’s website.
Todisable Windows updates, go toSettings>Windows Update>Advanced Options>Pause updates.
you’re free to pause updates for up to 35 days.
After that, automatic updates will resume.
Toupdate Windows drivers, go to the gadget Manager, right-nudge the target gadget, and selectUpdate Driver.
From there, you could automatically search or browse your setup for driver updates.