What does the "Activate Windows" watermark mean?

The short answer

The “Activate Windows” watermark means your copy of Windows isn’t activated with a valid product key, so Microsoft is reminding you to finish setting it up.

Why am I seeing this?

Windows requires a product key or digital license to confirm you’re using a legitimate copy. When it can’t verify that, a faint watermark appears in the bottom-right corner of your screen that says something like “Activate Windows — Go to Settings to activate Windows.”

Common reasons it shows up:

  • You installed Windows without entering a product key (you can skip this step during setup)
  • Your license expired or was deactivated after a hardware change like replacing your motherboard
  • You upgraded from an older version of Windows and the activation didn’t carry over
  • Your PC came with Windows, but the license got corrupted after a reset or reinstall

Is your computer still working?

Yes. An unactivated copy of Windows still works almost normally. The main limitations are:

  • The watermark stays on screen at all times, even over videos and games
  • You can’t personalize your desktop — changing wallpaper, colors, and themes is locked
  • You may not receive certain updates over time

Your files, apps, and core features are not affected.

How to fix it

  1. Open Settings and go to System > Activation
  2. If you have a product key, click Change product key and enter it
  3. If you bought your PC with Windows pre-installed, click Troubleshoot — this often reactivates it automatically
  4. If you recently changed hardware, select I changed hardware on this device recently and sign in with the Microsoft account linked to your license

If you don’t have a product key, you can buy one directly from Microsoft or from an authorized retailer.

When should you worry?

The watermark itself is harmless. But be cautious if:

  • Someone else set up your computer and you’re not sure where the copy of Windows came from
  • You’re seeing activation errors after buying what was sold as a “genuine” key — it may have been a gray-market or fake key
  • The watermark appeared suddenly on a PC that was previously activated — this could mean a license server issue or an unauthorized hardware change

If the watermark showed up out of nowhere on a previously working PC, try restarting first. If it persists, run the activation troubleshooter in Settings before spending money on a new key.