Analog refers to the signal format used to transmit today's television, also called NTSC. Digital signals also can transmit television, but they are much more efficient and can carry many times more information than analog. The highest quality digital TV signals will be high-definition or HDTV, are defined as either 720 lines or 1080 lines of vertical resolution. While the signals are different, today's analog sets will be able to receive the new digital signals by using a TeVCA adapter box.