Most of the Gospel of John is an account of the events of the last 20 days of the life of Jesus.
The
purpose of the book of John
"Jesus did many other miraculous signs in the presence of his
disciples, which are not recorded in this book. But these are
written that you may believe that Jesus is the Christ, the Son of
God, and that by believing you may have life in his name." (John 20:30,31)