The most important element in any story is its plot. A plot is the crystallized, distilled and dramatized version of a set of events that unfold in a particular order to a set of characters and how the given characters react to that situation leading to a logical and satisfactory ending or conclusion.

So, in essence, most plots follows the three-act structural model which comprises a beginning, middle and end. In the first act, the protagonist, his/her situation in life, their physical and mental characteristics, personality traits, their deeper motivations; their past history or back story that tell the readers why they are the way they are in their present, what they need, what they want are all introduced and established in a step by step manner.

A particular event which we will refer to as the inciting incident disrupts the existing status quo changing the direction of the protagonist's life and everyone surrounding him/her once and forever. It sets the ball rolling. The plot begins moving forward from this point onwards.

The protagonist must grapple with the situation and its wider implications throughout the middle act. Complications and conflict caused by external or internal factors prevent the protagonist from achieving his/her objective.

Things, events and reaction to events keep on piling one on top of the other till they reach the peak or the climax in the final act. At this point of no return, everything moves rapidly towards the resolution where everything ends happily, sadly, as a mixed bag or remains unresolved for the protagonist.

FIRST ACT: Exposition---> Inciting Incident

SECOND ACT: Rising Action---> Complications

THIRD ACT: Climax---> Falling Action---> Resolution

Most of the plots are linear in nature. They follow the chronological order of events. The occasional flashbacks or flash forwards don't essentially mean that the plot is non-linear as long as the events happening follow a chronological sequence.

But there are several stories whose plots are non-linear. The events presented are not in their chronological order. In this kind of plot, the story might begin with the end followed by the middle and finally end with the beginning. Or, it might keep on shifting and alternating between the beginning, middle and end multiple times. There might be numerous fractured versions of the same story. Each version is radically different from the other.