A movie might contain an emotional roller coaster of scenes, from fast moving action sequences to quiet conversations between characters. Similarly, according to Northern Illinois University, "A narrative is a moving picture" that the reader should "experience, not simply hear." The management of action and time throughout a story is called pacing. Authors develop pacing in narratives in a number of ways, including the creation of scenes and use of detail.
A scene is the basic unit of action in a narrative. Scenes dramatize the story's significant events by capturing them as a moment in time. Everything is portrayed directly for readers through dialogue and characterization, revealing conflict among characters, as well as their behaviors and reactions to plot developments. Scenes are important because they are cinematic, bringing the important incidents in the story to life as if they are happening before the reader's eyes. Scenes enforce pacing by moving through the incident chronologically, as it would happen in real time.
If an author wrote a story composed entirely of scenes, a lot of mundane actions would take place that don't need to be thoroughly described. Summary is used to eliminate detailed accounts of unimportant events. For example, a scene that describes the protagonist driving to work, drinking coffee and playing with his phone during which time nothing else happens doesn't do much to advance the plot; instead, the author could summarize the trip by saying, "He drove to work," then pick up the story after he arrives. Summary provides variation in pacing by briefly detailing the action that links one scene to another.
A flashback is a scene within a scene that transports readers back to a significant event that happened before the story. Flashbacks can be triggered by certain sensory details, plot development or seeing somebody that reminds him of his past. As the character thinks back to this event, the text depicts it for readers. Flashbacks figure into pacing because they manipulate time in a way that creates intrigue for readers and gives important back story. They must, however, be relevant to the story and reveal new information. If not, they will slow the pacing and the reader might lose interest.
Sometimes in a scene, it is necessary to slow the narration down so readers can take note of important things the main character sees. This is where including passages of description can be helpful. For example, if a character meets a girl he will later develop a relationship with, taking a moment to introduce her through memorable description will send a cue to readers that she will become important to the plot. Like flashbacks, description must advance the story and reveal new information and not simply be padding that brings the action to a stop.