HomePlug is a collection of specifications to use the current electricity networks for data and voice transmission. THe use of the the power lines for communication purposes is called Power Line Communications (PLC) or Power Line Transmission (PLT).
The HomePlug Alliance has made a number of specifications for different applications.
HomePlug 1.0 is the specification for a technology that connects devices to each other through the power lines in a home. HomePlug certified products connect PCs and other devices that use Ethernet, USB and 802.11 "Wi-Fi" technologies to the power line via a HomePlug "bridge" or "adapter". HomePlug 1.0 has a maximum data rate of 10 Mbit/s.
HomePlug AV was designed to support the high-bandwidth and low-latency demands of several simultaneous streams of HDTV and VoIP, made concurrently available in over 90% of power outlets in a home. The target applications are in-home distribution of audio-video in home-theater and data-networking environments. HomePlug AV will provide a 200 Mbit/s class service at the physical layer, around 130 Mbit/s is available for the applications.
Broadband Power Line (BPL) refers to a to-the-home technology to provide broadband internet access.
HomePlug Home Automation
HomePlug Home Automation is the specification of a low data rate robust technology to command-and-control applications by means of the power lines.