Authorship and Origin:

This is the third of the synoptic gospels and was written by 'the beloved physician' as the apostle Paul referred to him. Only in Luke are found the 'Magnificat', the story of the birth of John the Baptist, the Christmas story of the shepherds, the parables of the Good Samaritan, the lost sheep, and the prodigal son. Luke was a physician and a well educated man. He was familiar with the Eastern Mediterranean area and appears to have traveled with Paul from Troas to Philippi before 52 A.D. and then later after 58 A.D. Tradition has it that he came from the city of Antioch.

This gospel must have been written around 90 A.D. since some of it's content appears to be based on Mark. Luke writes in a Greek of high quality as is evident here and in the book of Acts for which he is also author. The books of Luke and Acts together comprise about a quarter of the New Testament. Luke writes a 'religious history' - that is, it is a biography, but also a proclamation - a theology of history.

Overview and Significant sections

Apparently, Luke felt a need to unify the varied and scattered accounts of Jesus' life and teachings that were present at this time. Luke's work contains notes of social, humanitarian, and historical interest, and is sometimes called the 'social gospel'. In fact much of our specific knowledge of Christianity comes from this gospel and the book of Acts. His book is apparently well planned in that it has a preface, dedication, and accounts of sources.

.. and many other parables...
For more detailed study:
Read Chapter 1. (the entire book is available here.)
The Concise Matthew Henry Commentary on this book. study of this book.
the World Wide Study Bible has Dictionary, Commentary, Scripture and sermons available on this book.