“The Gospels, the first four books of the New Testament, tell the life of Christ Jesus. But, there is only one, the Gospel of John, who claims to be an eyewitness account, the testimony of the unnamed “disciple whom Jesus loved.” (“This is the disciple who is testifying to these things and wrote these things, and we know that his testimony is true” [John 21:24]). (biblicalarchaeology.org)”
The author of the Gospel of John is the Apostle John. “Apostle John was the brother of the Apostle James; he was also the son of Zebedee (a fisherman of Galilee.) His mother's name was Salome who is believed to be a sister of Jesus' mother Mary. Apostle John owns a house in the city of Jerusalem and that it is possible that the interview Nicodemus had with Jesus was held there. (biblepath.com)”
“John later became the pastor of the church in Ephesus and had a special relationship with other churches in that area.”
John was a fisher man with his brother James and Apostle Peter before Christ called them. Apostle John died at the same city as Christ Jesus. "Founded and built churches throughout all Asia, and worn out by old age, died in the sixty-eight year after our Lord's passion and was buried near the same city (Ephesus)."