An inciting incident is an event that sets the plot of a book, movie or play into motion. This normally occurs after the background and setting have been given.
The inciting incident is usually followed by the rising action of the plot, which is the basic build up of conflict that leads to the climax. There may be several other points involved in the rising acting, but it should all stem from the inciting incident. The plot points that come after the inciting incident will always be related back to that point because it is the launching point that sets the character on a journey.