KMS stands for Key Management Services, which is a method used to activate Microsoft Windows and Microsoft Office products. KMS is used by volume license customers, usually medium to large businesses, schools, and non-profits. KMS activation is available for Windows Server, Windows client, and Microsoft Office products that are distributed by CU Software under Cornells Microsoft Campus Agreement site license.

To use KMS, you need to have a KMS host available on your local network. A KMS host is a server that contains the host key that the client uses for activation. KMS clients connect to the KMS host for activation. Once a KMS client is validated, the Microsoft product on that client contacts the server every 180 days to maintain its validity.

To activate Windows or Office products using KMS, you need a specific product key, which is sometimes referred to as the KMS client key, but its formally known as a Microsoft Generic Volume License Key (GVLK). Computers that are running volume licensing editions of Windows Server and Windows client are, by default, KMS clients with no extra configuration needed as the relevant GVLK is already there. However, there are some scenarios where youll need to add the GVLK to the computer you wish to activate against a KMS host, such as converting a computer from using a Multiple Activation Key (MAK), converting a retail license of Windows to a KMS client, or if the computer was previously a KMS host.

KMS activation is a legitimate way to activate Microsoft products without user intervention. It ensures that the software is obtained from and licensed by Microsoft. KMS clients must be activated at least once every 180 days. A KMS client will try to activate once every 7 days, and if it fails, it will try again every 2 hours.