Who was the author? While the Holy Spirit is the ultimate author of the book of Jude, the human author identifies himself as "Jude" a "brother of James", presumably both were "kinsmen" of our Lord, which could mean half-brothers, step-brothers, cousins, or as simple believers.
What is the book? The book is a letter to Christians troubled by false teachers; the specific recipients of the letter are not identified.
Where was it written? We do not know from where Jude was written, nor are there apparently enough clues to even make an educated guess.
When was it written? The dating of Jude depends in part on the dating of Peter and the decision as to which, if either, is depending on the other. Jude could have been written as early as A.D. 65 (or earlier) or as late as A.D. 80.
Why? Much like with 2 Peter, the letter targets false teachers, in this case specifically those who taught that Christian freedom included the freedom to sin.
How? Jude begins by assuring his hearers that they have been called by God, and he finishes by giving glory to the God who can keep them from departing that calling. In between Jude attacks the false teachers' impious life and otherwise encourages the believers.
For further reading on the book of Jude:
- Kretzmann, Paul E. Popular Commentary of the Bible: The New Testament, Volume II, The Epistles of the Apostle Paul, The Epistle to the Hebrews and the Catholic Epistles, the Book of Revelation. St. Louis: Concordia Publishing House, 1922. (There are 6 pages of comments on Jude in this commentary.)
- Lenski, R. C. H. The Interpretation of the Epistles of St. Peter, St. John and St. Jude. Minneapolis, MN: Augsburg Publishing House, 1961. (There are 55 pages specifically on Jude in this commentary.)