Microsoft Product Activation for Windows XP or Volume Activation for Windows 7 is an antipiracy technology that veriﬁes that software products are legitimately purchased. Product activation reduces a form of piracy known as casual copying. For example, you must activate Windows 7 within a given number of days after installation. After the grace period, users can- not access the system until they activate Windows. Volume Activation automates the activation process.
Figure: Product activation.
For individual installations of Windows, you can activate the installation over the Internet. If you do not have an Internet connection, you can activate over the phone, although this takes a little longer. If you wish, you can postpone product activation and activate later in the activation grace period.
In large organizations, you can use a Volume License Product Key, which eliminates the need to individually activate each installation of Windows. You can also activate Windows as part of an automated installation.
————- Thanks Everyone