Microsoft's official Windows activation methods involve either the customer entering a 25-character product key when prompted, or signing in with their Microsoft account to apply a digital license.

Microsoft has confirmed that Windows 7 and 8 keys can no longer activate any Windows 11 edition or version, not just Canary builds, as reported in September. However, Windows 10 keys are still valid.

Windows usually comes pre-installed on PCs but there may come a time when you need to find your computer's serial number on Windows.