The Third Epistle is to "Gaius the beloved", a notable believer. The name was a common one, and the bearer may not be of those mentioned in Acts , &c.
The probability is that both epistles were written from Ephesus and about the same time, but nothing is known definitely as to either place or time of writing.
The reader will readily see the Structure of these two short epistles. Each takes the form of an Introversion , the intermediate members marking exhortation and warning. The Third Epistle contains a personal element, commendation of Gaius and Demetrius, and condemnation of Diotrephes.