The document discusses key concepts from Everett Rogers' book Diffusion of Innovations including: 1) Diffusion is the process by which an innovation is communicated over time through certain channels among members of a social system. The main elements are the innovation, communication channels, time, and the social system. 2) Innovations have perceived attributes like relative advantage and complexity that influence their rate of adoption. Communication channels and opinion leaders also impact diffusion. 3) Diffusion research traditions developed across various fields and focused on topics like the rate of adoption, innovativeness, and consequences of innovations.