While the number of books in the Bible varies depending on faith, the Catholic, Orthodox and Protestant biblical canons have been static since roughly the fifth century, making the argument rare that books are missing. However, contemporaneously written books do exist that some argue should be included in the Bible.
Books that some argue should be included in Bible are typically given the name "apocrypha." Examples of New Testament apocrypha include the Epistle of Barnabas and the Didache.
Some books in the Old Testament included in the Orthodox and Catholic Bibles are considered apocryphal to the Protestant Bible, such as the Wisdom of Solomon and the books of the Maccabees. In all, the number of books included in the Old Testament ranges from 24 books in the Hebrew Bible to 51 books in the Orthodox Bible.