Flashback:
Returning to an earlier time in a narrative for the purpose  of making something in the present clearer. 


Example:

Because i could not stop for death
http://www.poets.org/viewmedia.php/prmMID/15395
-Emily Dickinson


Explanation:
Dickinson makes a large flashback in this poem to add to the emphasizes and feelings of sorrow that come with death. She has a flash back of all the stages of life. She does this on purpose to show she is reminiscing all the things that happen during life, and ends with death. The description of life adds to the feelings of sorrow and fear that is associated with death. It also adds to the purpose of accepting death.