The twentieth, and penultimate, of the Epistles is III John. It was written by Jesus' disciple sometime around 95 AD, most likely in Ephesus, a Greek city in modern day Turkey.
The letter talks about friendship and hospitality amongst Christians. At the time there were many itinerant preachers, whose mission was to travel the land, founding new churches and strengthening ones already established. These missionaries relied on their fellow believers' charity whilst on their travels, and III John tells Christians how they should treat them; and how they should not.