An open letter is a letter that is intended to be read by a wide audience, or a letter intended for an individual, but that is nonetheless widely distributed intentionally.[1][2]
Open letters usually take the form of a letter addressed to an individual but are provided to the public through newspapers and other media, such as a letter to the editor or blog.[3] Critical open letters addressed to political leaders are especially common.
Two of the most famous and influential open letters are J'accuse...! by Émile Zola to the President of France, accusing the French government of wrongfully convicting Alfred Dreyfus for alleged espionage; and Martin Luther King Jr.'s Letter from Birmingham Jail, including the famous quotation "Injustice anywhere is a threat to justice everywhere".[3]