Amazon RDS Custom is a managed database service that allows customization of the underlying database and operating system for business applications. It combines the automation of Amazon RDS with the ability to access and customize the database environment to meet specific requirements. RDS Custom enables installation of agents, drivers, patches, and custom workloads on the host with granular control. Organizations can easily migrate existing self-managed Oracle and Microsoft SQL Server databases that need specialized customizations to RDS Custom, eliminating the need to manage databases themselves.