The word apocrypha in Bibliology refers to texts that are not considered canonical, part of the Bible, but are of roughly similar style and age as the accepted Scriptures. Protestants use the word apocryph, in a narrower sense, of those books that they exclude from their canon of Scripture, but that other Churches view as canonical and venerate as divinely inspired, written under the influence of the Holy Spirit.
Disagreement between Christian Churches is almost non-existent about the canon of the New Testament, but the inclusion of some books in the Old Testament canon is disputed. Since these books were of late composition, Protestant scholars sometimes call them intertestamenta, i.e. intermediate between the Old and New Testaments, and hold that God imposed a period of silence, with no prophecy or Scripture, to prepare for the coming of Jesus.
The books that come under the description apocryph in the broad sense but not in this narrow sense are called apocrypha by Catholics and Jews, but Protestants usually call them Pseudepigrapha. Many of them have apocalyptic themes.