What is form criticism?

the long version

The purpose of form criticism is to determine which of the words or deeds attributed to Jesus go back to Jesus himself and which are likely to be the product of the early Church. The author begins his analysis of form criticism with a brief historical survey of the development of critical New Testament scholarship from the eighteenth century. He then describes the pioneer efforts of Martin Dibelius and Rudolf Bultmann in applying form criticism to the Synoptic Gospels. He believes that the form critical work of some contemporary scholars has greatly enriched our understanding of the Parables, and has added much to our knowledge about the historical Jesus.