The Gospel of Luke is the third of the canon gospels registered in the bible. It was written by a gentile. It starts with a salutation and the purpose which it was written. It was written as testimony to Theophilus, a good friend of Luke.

Luke made his own investigation about the things that had happened in Jerusalem. Luke gather the testimony of those who knew Jesus. He presents the genealogy of Jesus and the story of Elizabeth and John the baptist.

To learn important fats about the gospel of Luke, visit Wikipedia
And also The Catholic Encyclopedia