Analog - A continuously varying electronic signal. Audio and video analog signals stored on tape deteriorate with each copy or generation. In contrast, it is digital.
Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors, and sound are represented by amplitude, phase, and frequency of the analog signal.
https://www.youtube.com/watch?v=BCrZWu1wObU&feature=youtu.be