This section is for tutorials on all PC computer that run Windows.
A Windows COA (Certificate of Authenticity) is a label with your Windows product key printed on it. The product key validates your copy of Windows to be genuine and cannot be copied or used on any other system. The COA also tells you which version of Windows your computer is running if you are not sure. The COA can be found on the bottom or underneath the battery, for laptops; For desktops it can be found on the sides, on top or underneath.
The COA is worth around $150 added value to your computer; When it is faded or tampered with that's value lost. When a computer is missing the COA it cannot be legally sold with Windows installed on it, even if the computer is running perfectly fine.
There is also the case where a computer may have an operating system installed that is different than the one the computer came with. In this case there are a couple things that can happen. (1)If the computer is, for example, a Windows 8 computer with Windows 7 installed, and the manufacture warranty is still active you (or the buyer) can attain the original restore discs and this will not depreciate the value of your machine. (2)If the computer has a Windows 7 Home product key but has Windows 7 Ultimate installed, with no recovery media you will lose value on the computer.
There is a happy ending for newer laptops with Windows 8. Microsoft has changed the COA from a physical sticker to being inside of the system itself (the BIOS). This will stop users from dealing with missing or faded keys cause it will always be located within the system itself.
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