an event
The plot and sub-plots are what "happens" in a story.
That is called the plot of the story
That is called the setting of the story.
an explanation of how or why something happens is called a hypothesis.
That is called the setting
A verb form used to show when something happens is called tense.
twice-a-day or it can be called semi-diurnal which relates to such occurrences as tides.
A reason for why something happens is called a "cause." It refers to the factor or circumstance that leads to a particular effect or outcome.
Something. Seriously. Every story has something happen or it's a boring story. You need conflict and tension for it to be interesting, and that's when things happen.
Karma
An origin story.
Cause is how something happend an effect is what happens