Definition: The product key, often called a key code or installation key, is a usually unique, alphanumeric code of any length required by many software programs during installation. Unique product keys help software manufacturers ensure that each copy of their software was legally purchased.
All Microsoft Windows operating system versions require the entry of unique product keys during the installation process, as do all versions of Microsoft Office and most other Microsoft retail programs. Microsoft product keys are often located on a product key sticker, as shown here.
Even non-Microsoft operating systems and programs from most popular software makers require product keys. As a general rule these days, if you pay for a program then it probably requires a product key during install.
In most versions of Windows and other Microsoft software, product keys are 25-characters in length and contain both letters and numbers.
Below are some examples of what Microsoft Windows product keys look like:
- Windows 8: xxxxx-xxxxx-xxxxx-xxxxx-xxxxx
- Windows 7: xxxxx-xxxxx-xxxxx-xxxxx-xxxxx
- Windows Server 2008: xxxxx-xxxxx-xxxxx-xxxxx-xxxxx
- Windows Vista: xxxxx-xxxxx-xxxxx-xxxxx-xxxxx
- Windows Server 2003: xxxxx-xxxxx-xxxxx-xxxxx-xxxxx
- Windows XP: xxxxx-xxxxx-xxxxx-xxxxx-xxxxx
- Windows 2000: xxxxx-xxxxx-xxxxx-xxxxx-xxxxx
- Windows ME: xxxxx-xxxxx-xxxxx-xxxxx-xxxxx
- Windows 98: xxxxx-xxxxx-xxxxx-xxxxx-xxxxx
- Windows NT: xxxxx-xxx-xxxxxxx-xxxxx
- Windows 95: xxxxx-xxx-xxxxxxx-xxxxx
Important: See my Windows Product Key FAQ for more information about Windows keys.
In addition to product keys, some software makers, including Microsoft, often require product activation to help further ensure that software is obtained legally.
Since product keys are required during installation, finding that you've lost a product key could be a serious problem if you need to reinstall a program. Luckily, there are a number of ways to retrieve lost product keys:
Important Note: The unique product key entered for an operating system or a software program is typically stored in an encrypted format in the Windows Registry, making finding one very difficult without some help. The above linked guides should help find just about any CD key you may be looking for.
Also Known As: CD key, key code, product code, installation key
Examples: "I was getting ready to reinstall Microsoft Office 2010 but I realized I had thrown away the product key along with the manual! No worry - I downloaded a product key finder program and it showed me the Office 2010 key from my currently installed copy. I wrote it down this time!"
Product key image is © Microsoft.