Flashbacks are generally used in stories to gain insight on a characters past. These flashbacks may reveal past mistakes, triumphs, milestones, or relationships experienced by the certain character.
Flashbacks are a useful tool in storytelling because they can explain why a character acted a certain way towards a present situation.
You can also utilize the flashbacks to determine how a character might act in the future, or the choices a character might make.
While others might not know why a character acted a certain way, the reader does because you have insight on their past.
