The concept of obscenity (etymologically meanining "[things] to be kept far from visibility"--from Latin obscenitas) has several connotations. It can simply be used to mean profanity, or it can mean anything that is taboo, indecent, abhorrent, or disgusting. It is most commonly used to describe expression (words, images, actions) that offend sexual morality.
The definition of obscenity differs from culture to culture, between communities within a single culture, and also between individuals within those communities. Many cultures have produced laws to define what is considered to be obscene, and censorship is often used to try to suppress or control materials that are obscene under these definitions, usually including, but not limited to pornographic material.
Because the concept of obscenity is ill-defined, it is often used as a political tool to try to restrict freedom of expression. Thus, the definition of obscenity can be a civil liberties issue. The United States has constitutional protection for freedom of speech, and the definition of obscenity in that country has been the subject of much litigation and debate. The current US legal definition of obscenity is that of the Miller test.
Many historically important works have been described as obscene, or prosecuted under obscenity laws. For example, the works of Charles-Pierre Baudelaire, Lenny Bruce, William S. Burroughs, James Joyce, D. H. Lawrence, Henry Miller, and the Marquis de Sade.
See also: Blasphemy