The document discusses radio as a mass communication medium, particularly in rural areas of India. It notes that radio is an effective way to inform people and raise awareness on social issues. With its penetration into rural areas, radio is also becoming an important advertising medium for local audiences. Some key advantages of radio mentioned are that it caters to large rural populations without access to television or power, and can disseminate information widely through transistors. The document provides a brief history of radio and All India Radio in India. It also compares radio and television, noting their different prime times and costs.