A Windows 7 Home Premium Product Key is a 25-character code used to activate and validate the authenticity of the Windows 7 Home Premium operating system. This key ensures that the software is genuine and grants access to all features of the Home Premium edition.

The key typically follows the format: XXXXX-XXXXX-XXXXX-XXXXX-XXXXX.

It is required during installation or when making major hardware changes to the system. The product key can usually be found on the packaging or in an email if purchased digitally.