There is worldwide attention to disinformation, including its antecedents, production, distribution, and consequences. The attention spans across academic research, civil society, journalism, politics, and policy circles, and it has become part of public and popular discourse. However, the comprehensive attention also underscores the multifaceted nature of the phenomenon and very important social, cultural, and political context differences. This applies to the causes of the phenomenon, to the actors involved, the nature and fabrics of disinformation, the different dynamics of spread and the different kinds of individual and societal effects. In this chapter, we provide a brief introduction to the concept of disinformation and a conceptual overview. We discuss how different actors play different roles in the disinformation ecosystem and how individual and contextual factors affect the dynamics and effects of disinformation.