John, the author of the Gospel of John, as indicated by this book's comparable style and tone.

Approximately A.D. 90—95, after John's return from exile on Patmos, according to church history and the content of this book.

Ephesus, where, according to church history, John ministered in his last days.

The believers in general, who have the eternal life of God by believing into the Son of God (5:11-13).