UPnP (Universal Plug and Play) is a set of computer network protocols promulgated by the UPnP Forum. The goals of UPnP are to allow devices to connect seamlessly and to simplify the implementation of networks in the home and corporate environments. UPnP achieves this by defining and publishing UPnP device control protocols built upon open, Internet-based communication standards.
UPnP is distinct from Plug-and-play, a technology for dynamically attaching devices to a computer directly.
Read more at wikipedia -> UPnP (Universal Plug and Play)