Apocrypha: Books which are considered to be useful for study but which are not considered to be part of the scriptural canon. There is significant disagreement among the various denominations as to which books are in each group.
Most of the books create a bridge across the 400 years between the Old and New Testaments. There are a few other individual books only accepted by one or two religious traditions. The books are primarily of Jewish origin but some Christian groups also accept other books of a Christian origin.
Protestants generally deny the canonicity of the books and either include them in a separate section of the Bible or omit them entirely.