What term describes systems that are controlled and maintained at the customer's site?

The term that describes systems controlled and maintained at the customer's site is known as Client-Side KMS (Key Management Service). This designation highlights that the management of encryption keys occurs on the client's premises rather than being managed by a third-party provider or in a cloud infrastructure.

Client-Side KMS is particularly significant in contexts where organizations need to retain full control over their data security policies and practices. By managing the keys locally, organizations can implement specific access controls, compliance standards, and internal security protocols that are tailored to their unique requirements. This can be crucial in industries with stringent regulatory demands where data privacy and security are paramount.

In contrast, other options refer to key management solutions that might be hosted remotely, such as in the cloud or managed by third-party services. These alternatives do not align with the concept of systems that remain on the customer’s premises.