We seem to mention the Apocrypha fairly often. The answer to what they are is not simple. From the Greek (meaning “obscure”) through Medieval Latin (where it meant “secret, or non-canonical”), the word refers to a set or sets of texts the origin of which is doubtful or unknown. (“Canonical” refers to being ordained by Catholic law or being a part of the Gospels of the New Testament.
There are “Biblical apocrypha,” which include texts in the Latin Vulgate and Septuagint but not in Tanakh. Catholics hold some of the texts which Protestants consider apocryphal to be “deuterocanonical” (a part of their Bible, forming a second canon, such as parts of the Old Testament). Protestant Bibles may include these texts in a separate section, but not within their Old Testament proper. There are some non-canonical apocryphal texts which are lumped under the term “pseudepigrapha,” or “false writings.” And Jews don’t have an official list at all, generally including anything that is found as being of interest; thus, I don’t even know whether to capitalize “Apocrypha”!
Early on, the term was applied to religion-based writings which were kept secret from the masses, such as the secret books of Zoroaster possessed by the Gnostics. Earlier, as Christianity was taking hold, writings of Grecian Jewish origin - “intertestamental,” or between the testaments - were considered to be “hidden books” of the Bible. First and Second Maccabees are among the books that may be included by Christians (and we hold them outside as well, even though they hold our only account of the Hanukkah story). Eastern Orthodox also include Third and Fourth Maccabees, which don’t refer to Maccabees but detail conflicts between the Jews of Egypt and Ptolemy IV (221-203 BCE), and stories of martyrs. Most commonly also included are Books 1 and 2 of Esdras (tangential to the story of Esther), Tobit, Judith, The Letter of Jeremiah, The Prayer of Azariah and Song of the Three Young Men, Bel and the Dragon, and several others.
Various Christians have debated what parts of Jewish texts to include and why or why not. For instance, the King James Bible (published in 1611) included some intertestamental books, much as Catholics included them, but according to KingJamesBibleOnline they were removed by Protestants in 1885. Note that the King James, holding the most common set of Apocrypha, includes neither the Book of Enoch nor the Sibylline Oracles, previously mentioned in this column.
Whether or not these various ancient texts are considered a part of the holy books of any religion, we now live in an era in which we can reference the Dead Sea Scrolls (written in various languages between around 400 BCE to 320 CE) and discovered in the 1940s. We are free to value the history and learning potential embodied in those and any other writings, rather than debating whether or not they are holy to our religious tradition.