Censorship is defined as the restriction of public expression or access to information by an authority when the information may undermine the authority by making it accountable to the public. In this entry, I highlight that censorship has two objectives: to restrict freedom of expression and to prevent individuals or organizations from accessing specific information. After providing a definition for censorship and illustrating how it differs from other concepts, namely repression and propaganda, I give an overview of different forms of traditional and digital censorship tools. Next, I introduce prominent theories and empirical evidence that explore why governments censor. Then, I turn attention to studies that explore the consequences of censorship. I conclude by highlighting current areas of inquiry.