Dissent is a sentiment or philosophy of non-agreement or opposition to a prevailing idea (e.g., a government's policies) or an entity (e.g., an individual or political party which supports such policies). The term's antonyms include agreement, consensus (when all or nearly all parties agree on something) and consent, when one party agrees to a proposition made by another.
In some political systems, dissent may be formally expressed by way of opposition politics, while politically repressive regimes may prohibit any form of dissent, leading to suppression of dissent and the encouragement of social or political activism. Individuals who do not conform or support the policies of certain states are known as "dissidents". Several thinkers have argued that a healthy society needs not only to protect, but also to encourage dissent.