An application delivery controller (ADC) is a network device that manages client connections to complex Web and enterprise applications. In general, a controller is a hardware device or a software program that manages or directs the flow of data between two entities.
Software-defined networking (SDN) is an approach to networking in which control is decoupled from the physical infrastructure, allowing network administrators to support a network fabric across multi-vendor equipment.
Software-defined storage (SDS) is an approach to data storage in which the programming that controls storage-related tasks is decoupled from the physical storage hardware. Software-defined storage is part of a larger industry trend that includes software-defined networking (SDN) and software-defined data centers (SDDC).