In electronics and computing, a plug-and-play device or a plug-and-play interface protocol, is one with a specification that facilitates the discovery of a hardware component in a system without the need for physical device configuration or user intervention in resolving resource conflicts. Such plug-and-play devices may be used in connection with plug-and-play compatible computers, handheld devices, personal audio devices (e.g., wireless telephones, mobile/cellular telephones, cordless telephones, mp3 players, and other consumer audio devices), and other host devices.
A common feature of plug-and-play interface protocols (e.g., Universal Serial Bus (USB)) is the discovery of capabilities of an attached device by a host. As devices become more complex, presenting a full account of their capabilities presents several problems. First, a simple host may not have the ability to understand or process the complex set of full device capabilities. Second, a device may, by design or use, only support a subset of its full capabilities at any one time.