Apocrypha are written works, often of unknown authorship or doubtful origin. In Christianity, the word apocryphal (ἀπόκρυφος) was first applied to writings which were to be read privately rather than in the public context of church services -- edifying Christian works which were not considered canonical Scripture. In the wake of the Protestant Reformation, the word apocrypha came to mean "false, spurious, bad, or heretical".

From a Protestant point of view, Biblical apocrypha are a set of texts included in the Septuagint and the Latin Vulgate, but not in the Hebrew Bible. While Catholic tradition considers some of these texts to be deuterocanonical, and the Orthodox Churches consider them all to be canonical, Protestants consider them apocryphal, that is, non-canonical books that are useful for instruction. Luther's Bible placed them in a separate section in between the Old Testament and New Testament called the Apocrypha, a convention followed by subsequent Protestant Bibles. Other non-canonical apocryphal texts are generally called pseudepigrapha, a term that means "false attribution".