For many years stories about Jesus were passed on by word of mouth.  When a story is repeated again and again, it becomes shorter.  Proper names drop out, numbers are confused,  but the point of the story is preserved and emphasised.  This is why the first three gospels are largely made up of short anecdotes about Jesus, often leading up to an act of power or some great saying.  These anecdotes are not arranged in any special order.

As the Apostles and other eye-witnesses died or were martyred, it was seen to be important to write down a true record of Jesus' acts and teachings so as to prevent falsehood from creeping in. This movement began in the sixties of the first century and Luke 1:1  tells us that many such gospel books were compiled.  The church finally selected the four gospels as containing full, reliable information about Jesus.  The first three gospels are called "Synoptic" because treating the same material and using similar styles, they can profitably be compared with one another.  John's gospel is very different from the other three.  He sees Christ as from the "Beginning".