What is setting?

the diction and syntax that creates the style in a piece of writing

the central message or insight revealed through a story

the time, place, and social/historical context in which a story takes place

the central message or insight revealed through a story and that applies to anyone, anywhere

the time, place, and social/historical context in which a story takes place

Explanation:

A setting is where or when (or both, actually) the story is situated. As in, "England, during the Victorian Era". Another example would be "300 years in the future", or "in mars" or even both "300 years in the future, in mars".

By definition, a setting is: "the place or type of surroundings where something is positioned or where an event takes place."

because they were not just any seashells they were sally's seashells