Telling is most effective when used as a quick delivery. This can be of an emotional event, such as a character dying, or of backstory that is important to know but would bog down a work too much to show. Take this example of backstory from a short story of mine, told from Merlin’s perspective after he’s finished teaching the Lady of the Lake his magic:
He nodded, glad to see she was still asking questions. Seeing somebody flourish under his guidance reminded him of the times he had spent with Arthur.
The second sentence here is telling Merlin’s past. Since most people know or at least understand a close student/teacher relationship, I imply that Merlin is feeling the same relationship with the Lady of the Lake. I could have given a flash-back of Merlin teaching Arthur, which would have been showing, but the story was better off with this short mention of the past. And since Arthur plays no roll in this story, mentioning him would distract from the relationship at hand: the one between Merlin and the Lady of the Lake.
For an emotional event, a punchy, telling line works best after a build up of situation and feelings. If you want to tell of a character dying, for example, build up how much he means to at least one character for as long as possible. This time can vary; it can be one paragraph or two hundred pages. It all depends on how long it takes to establish the proper relationships with the characters.
I will say that an emotional event can be shown well. It is my personal opinion that the most tear jerking, hit you in the gut emotional scenes have the realization as a telling line. To give an example:
He stopped breathing. I knew he wasn’t going to start again.
That line can fit with any premise of a “he” dying. Both sentences are telling, yet they have an emotional reaction. We are told his chest stopped moving, and we are told what the MC [Main Character] knows. A showing line would look something like,
His breathing slowed to where I couldn’t hear it anymore. I put my hand above his mouth and nose to see if he was breathing. I felt no air against my skin.
So, not half bad. There’s still a heart-tugging reaction, but keep in mind these are isolated events. Say that “he” is the MC’s boyfriend and he had a knack for making it out of life and death situations alive. I think telling us he’s dead would work better in that case, because there’s a higher expectation that he’ll make it. Two telling lines kicks our feet out from under us. The three showing lines are a slow build up to him dying.
A rather obscure use of telling is “telling details.” Those are usually little lines of description that dig down to a deeper meaning in the work. This description is usually a metaphor, simile or other form of figurative language which at the beginning of the work doesn’t look all that important, but come the end you realize just what all those metaphors meant. They can also show the theme of a work. In a novel I’m planning, I use hot and cold as a metaphor for feeling emotions and being numb, respectively. Despite the bad pun that makes, those details make it so the story and world take center stage, not any meaning I might be trying to get.
The dark side of telling is why the “show, don’t tell” rule is used. If done poorly, telling makes a work too fast and flat to read. Nothing is left to the reader to imagine, and important events seem to be glazed over because in one line, the emotion is over because we were told. But if done well, telling is the cornerstone of a work. In fact, if you show too much in a work, it can be just as bad as telling too much. Showing every event can get boring to write and boring to read very quickly. A rule of thumb I use for backstory is: If the scenes themselves are not vital to the plot, tell them. This doesn’t mean that what happened in those scenes isn’t important; it means that I could pace the story better by summarizing (i.e.- telling) a scene instead of showing it.
To give an example of a scene that should be told, and not shown, let’s say that the MC lost her dad in an accident, and it now affects not only her relationships to her mom’s boyfriends, but she’s got a fear of whatever killed her father (I’ll let you fill in that blank). You could show her getting the news of her father’s death, the whole reaction to that, and a bunch of other scenes that show interactions between her mother, mother’s boyfriends, and what killed her father, OR you could give us maybe a page of summery of how she feels and move on. Needless to say, the later option is the better choice. It’s less repetitive, less long, and tells us the same thing. Now the plot can move on in whatever direction you want.
Telling can be one of the best tools you use in fiction. It can deliver a quick punch that makes readers empathize with the MC, summarize a scene so the plot could keep moving, and, if properly used, can create a deeper meaning in a story. Using telling well is the difference between a good work of fiction and a great one.

