KMS, or Key Management Service, is a technology developed by Microsoft to facilitate the activation of volume licenses for Windows and Office products. It works by allowing organizations to set up their own activation server, enabling the activation of Microsoft products without needing to connect to Microsoft’s servers directly. When a device is activated via KMS, it communicates with the KMS host to verify the license. This is particularly useful for businesses that deploy multiple licenses, as it simplifies the management and reduces the number of activations that need to be handled individually.