The Book of Enoch — more precisely 1 Enoch, to distinguish it from later works that travel under similar names — is a composite Jewish apocalyptic work that grew across several centuries. It was widely read in Second Temple Judaism and in the early Church, and survives in complete form only in Ge’ez (the classical language of Ethiopian Christianity); substantial Aramaic fragments turned up among the Dead Sea Scrolls, confirming its ancient circulation.
The book divides into five major sections. The Book of the Watchers (chapters 1–36) expands the brief, cryptic note in Genesis 6:1–4↗ about the “sons of God” who took human wives, recounting the fall of two hundred angels under the leader Semjaza, the giants born to them, and the corruption that followed. The Book of Parables (chapters 37–71) contains visions of judgment and an exalted heavenly “Son of Man” figure. The Astronomical Book (chapters 72–82) presents a solar-calendar cosmology attributed to Enoch. The Book of Dream Visions (chapters 83–90) is a sweeping symbolic history of Israel. The Epistle of Enoch (chapters 91–108) is an exhortation and apocalyptic conclusion.
For Christian readers the most striking fact is that the New Testament quotes 1 Enoch directly. The epistle of Jude attributes a prophecy to “Enoch, the seventh from Adam” (Jude 1:14–15↗), quoting nearly verbatim what we now have as 1 Enoch 1:9. For Latter-day Saint readers, 1 Enoch sits alongside Moses 6–7 in the Pearl of Great Price, where Joseph Smith’s revision of Genesis records a substantial body of Enoch material — including the founding of the city of Zion (Moses 7:18↗) — that the Bible does not contain.
The Book of Enoch is not scripture in either the Christian or Latter-day Saint canons, but the breadth of the Enoch tradition it preserves makes it indispensable background for reading the canonical Enoch material in both testaments.