Referendum is a type of election in which voters directly vote on a specific issue. They are usually binding, but can also be consultative. Referenda are often held to repeal or amend laws, but can be used to change a constitution or even to launch wars.
A referendum is a form of direct democracy and, in some countries, is more popular than electoral votes to elect governments. Proponents argue that it provides legitimacy to political decisions because it allows citizens to decide issues themselves instead of having them imposed on them by the executive or legislative branch. Critics, however, argue that a referendum can be skewed by media coverage, propaganda, strong personalities and expensive advertising campaigns. They further claim that it can lead to short-term whims and is not well suited for complex or technical questions.
Whether or not a referendum is valid depends on the law and constitution of each country, state or organization. Some of them require a certain percentage or turnout in order to be legally valid, and others have different rules about what needs to be included on the ballot to make it a referendum.
A referendum can be called for by the executive, legislature or a petitioned by citizens (often through the popular initiative process). The wording of the question can vary widely. In some cases the results are binding, but in other cases the governing body can choose to ignore them. The United States has no referendum elections, but some of its states do.