What is a product key?

Watch a video about where to find your product key. (To view captions in your language, tap or click the Closed captioning button Closed Captioning button.)

A product key is a 25-character code that's used to activate Windows. Activation helps verify that Windows hasn't been used on more PCs than the Microsoft Software License Terms allow.

Your product key is on a card inside the box that the Windows DVD came in—or in an email that shows that you bought Windows. It looks like this: PRODUCT KEY: XXXXX-XXXXX-XXXXX-XXXXX-XXXXX. If you bought a PC with Windows preinstalled, contact the PC manufacturer for the original key.

It's a good idea to save a copy of your product key for your records in case you ever need to reinstall Windows.

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