1 Chapter, 13 verses, 303 words.
The author is John the apostle. Obvious similarities to 1 John and the Gospel of John suggest that the same person wrote all three books. Compare the following:
See introduction to 1 John and the Gospel of John: Author.
The letter was probably written about the same time as 1 John (A.D. 85-95), as the above comparisons suggest.
Occasion and Purpose
During the first two centuries the gospel was taken from place to place by traveling evangelist and teachers. Believers customarily took these missionaries in their homes and gave them provisions for their journey when they left. Since Gnostic teachers also relied on this practice (3Jn 5), 2 John was written to urge discernment in supporting traveling teachers; otherwise, someone might unintentionally contribute to the propagation of heresy rather than truth.