As a relatively new area in the communication discipline, health communication research typically has focused more on communication in formal health care and health promotion contexts than on informal or everyday communication that affects health and risk attitudes, beliefs, behaviors, and outcomes. Traditionally, health communication research focused heavily on planned messages and message design, health communication campaigns, and communication programs to promote health. Likewise, much research centered on communication in formal health care contexts. However, as the field has evolved, researchers have recognized the significant roles in health and risk played by everyday or incidental messages. From a systemic perspective, health communication can be construed as occurring in a matrix of both formal and informal communication contexts in which planned and incidental, everyday messages abound, ...